feat(flutter): discover screen — search Lidarr + create requests

- models/lidarr.dart (LidarrSearchResult + LidarrRequestKind)
- api/endpoints/discover.dart (search + createRequest)
- discover/discover_screen.dart with TextField, kind toggle (Artists/Albums),
  results list with in_library / requested pills
- /discover route + explore icon on home AppBar (5 actions now: Library,
  Playlists, Search, Discover, Settings)

flutter_client/lib/api/endpoints/discover.dart

@@ -0,0 +1,59 @@
+import 'package:dio/dio.dart';
+
+import '../../models/lidarr.dart';
+
+class DiscoverApi {
+  DiscoverApi(this._dio);
+  final Dio _dio;
+
+  /// GET /api/lidarr/search?q=...&kind=artist|album|track. Server has a
+  /// 60s LRU cache for repeat queries so re-typing the same string in
+  /// quick succession is cheap.
+  Future<List<LidarrSearchResult>> search(
+    String query,
+    LidarrRequestKind kind,
+  ) async {
+    final r = await _dio.get<List<dynamic>>(
+      '/api/lidarr/search',
+      queryParameters: {'q': query, 'kind': kind.wire},
+    );
+    final raw = r.data ?? const [];
+    return raw
+        .map((e) =>
+            LidarrSearchResult.fromJson((e as Map).cast<String, dynamic>()))
+        .toList(growable: false);
+  }
+
+  /// POST /api/requests. Returns the newly-created LidarrRequest body
+  /// — we don't expose a typed wrapper for that yet on mobile (admin
+  /// reviews requests; user just kicks them off), so we discard the
+  /// response and surface success/failure to the caller.
+  Future<void> createRequest({
+    required LidarrRequestKind kind,
+    required String artistMbid,
+    required String artistName,
+    String? albumMbid,
+    String? albumTitle,
+    String? trackMbid,
+    String? trackTitle,
+  }) async {
+    final body = <String, dynamic>{
+      'kind': kind.wire,
+      'lidarr_artist_mbid': artistMbid,
+      'artist_name': artistName,
+    };
+    if (albumMbid != null && albumMbid.isNotEmpty) {
+      body['lidarr_album_mbid'] = albumMbid;
+    }
+    if (trackMbid != null && trackMbid.isNotEmpty) {
+      body['lidarr_track_mbid'] = trackMbid;
+    }
+    if (albumTitle != null && albumTitle.isNotEmpty) {
+      body['album_title'] = albumTitle;
+    }
+    if (trackTitle != null && trackTitle.isNotEmpty) {
+      body['track_title'] = trackTitle;
+    }
+    await _dio.post<Map<String, dynamic>>('/api/requests', data: body);
+  }
+}

flutter_client/lib/discover/discover_screen.dart

@@ -0,0 +1,261 @@
+import 'package:dio/dio.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:go_router/go_router.dart';
+
+import '../api/endpoints/discover.dart';
+import '../api/errors.dart';
+import '../library/library_providers.dart' show dioProvider;
+import '../models/lidarr.dart';
+import '../theme/theme_extension.dart';
+
+final _discoverApiProvider = FutureProvider<DiscoverApi>((ref) async {
+  return DiscoverApi(await ref.watch(dioProvider.future));
+});
+
+class DiscoverScreen extends ConsumerStatefulWidget {
+  const DiscoverScreen({super.key});
+
+  @override
+  ConsumerState<DiscoverScreen> createState() => _DiscoverScreenState();
+}
+
+class _DiscoverScreenState extends ConsumerState<DiscoverScreen> {
+  final _ctrl = TextEditingController();
+  LidarrRequestKind _kind = LidarrRequestKind.artist;
+  Future<List<LidarrSearchResult>>? _resultsFuture;
+
+  @override
+  void dispose() {
+    _ctrl.dispose();
+    super.dispose();
+  }
+
+  void _runSearch() {
+    final q = _ctrl.text.trim();
+    if (q.isEmpty) {
+      setState(() => _resultsFuture = null);
+      return;
+    }
+    setState(() {
+      _resultsFuture = ref
+          .read(_discoverApiProvider.future)
+          .then((api) => api.search(q, _kind));
+    });
+  }
+
+  Future<void> _request(LidarrSearchResult row) async {
+    final fs = Theme.of(context).extension<FabledSwordTheme>()!;
+    try {
+      final api = await ref.read(_discoverApiProvider.future);
+      await api.createRequest(
+        kind: _kind,
+        artistMbid: _kind == LidarrRequestKind.artist ? row.mbid : row.artistMbid,
+        artistName: _kind == LidarrRequestKind.artist ? row.name : row.secondaryText,
+        albumMbid: _kind == LidarrRequestKind.album ? row.mbid : null,
+        albumTitle: _kind == LidarrRequestKind.album ? row.name : null,
+      );
+      if (mounted) {
+        ScaffoldMessenger.of(context).showSnackBar(SnackBar(
+          content: Text('Requested: ${row.name}'),
+          backgroundColor: fs.iron,
+        ));
+        // Re-run search to refresh the `requested` flag on the row.
+        _runSearch();
+      }
+    } on DioException catch (e) {
+      if (mounted) {
+        final code = ApiError.fromDio(e).code;
+        ScaffoldMessenger.of(context).showSnackBar(SnackBar(
+          content: Text('Request failed: $code'),
+          backgroundColor: fs.error,
+        ));
+      }
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final fs = Theme.of(context).extension<FabledSwordTheme>()!;
+    return Scaffold(
+      backgroundColor: fs.obsidian,
+      appBar: AppBar(
+        backgroundColor: fs.obsidian,
+        elevation: 0,
+        leading: IconButton(
+          icon: Icon(Icons.arrow_back, color: fs.parchment),
+          onPressed: () => context.pop(),
+        ),
+        title: Text('Discover', style: TextStyle(color: fs.parchment)),
+      ),
+      body: Column(children: [
+        Padding(
+          padding: const EdgeInsets.fromLTRB(16, 8, 16, 4),
+          child: Row(children: [
+            Expanded(
+              child: TextField(
+                controller: _ctrl,
+                style: TextStyle(color: fs.parchment),
+                cursorColor: fs.accent,
+                onSubmitted: (_) => _runSearch(),
+                decoration: InputDecoration(
+                  hintText: 'Search Lidarr for new music',
+                  hintStyle: TextStyle(color: fs.ash),
+                  enabledBorder: OutlineInputBorder(
+                    borderSide: BorderSide(color: fs.iron),
+                  ),
+                  focusedBorder: OutlineInputBorder(
+                    borderSide: BorderSide(color: fs.accent),
+                  ),
+                  suffixIcon: IconButton(
+                    icon: Icon(Icons.search, color: fs.ash),
+                    onPressed: _runSearch,
+                  ),
+                ),
+              ),
+            ),
+          ]),
+        ),
+        Padding(
+          padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 4),
+          child: SegmentedButton<LidarrRequestKind>(
+            segments: const [
+              ButtonSegment(value: LidarrRequestKind.artist, label: Text('Artists')),
+              ButtonSegment(value: LidarrRequestKind.album, label: Text('Albums')),
+            ],
+            selected: {_kind},
+            onSelectionChanged: (s) {
+              setState(() {
+                _kind = s.first;
+                if (_ctrl.text.trim().isNotEmpty) _runSearch();
+              });
+            },
+          ),
+        ),
+        Expanded(
+          child: _resultsFuture == null
+              ? Center(
+                  child: Text(
+                    'Type to search, then tap Request to send to Lidarr.',
+                    textAlign: TextAlign.center,
+                    style: TextStyle(color: fs.ash),
+                  ),
+                )
+              : FutureBuilder<List<LidarrSearchResult>>(
+                  future: _resultsFuture,
+                  builder: (ctx, snap) {
+                    if (snap.connectionState != ConnectionState.done) {
+                      return const Center(child: CircularProgressIndicator());
+                    }
+                    if (snap.hasError) {
+                      final err = snap.error;
+                      final code = err is DioException
+                          ? ApiError.fromDio(err).code
+                          : 'unknown';
+                      return Center(
+                        child: Text('Search failed: $code',
+                            style: TextStyle(color: fs.error)),
+                      );
+                    }
+                    final rows = snap.data ?? const [];
+                    if (rows.isEmpty) {
+                      return Center(
+                        child: Text('No matches.',
+                            style: TextStyle(color: fs.ash)),
+                      );
+                    }
+                    return ListView.separated(
+                      itemCount: rows.length,
+                      separatorBuilder: (_, __) =>
+                          Divider(height: 1, color: fs.iron),
+                      itemBuilder: (ctx, i) => _ResultTile(
+                        row: rows[i],
+                        onRequest: () => _request(rows[i]),
+                      ),
+                    );
+                  },
+                ),
+        ),
+      ]),
+    );
+  }
+}
+
+class _ResultTile extends StatelessWidget {
+  const _ResultTile({required this.row, required this.onRequest});
+  final LidarrSearchResult row;
+  final VoidCallback onRequest;
+
+  @override
+  Widget build(BuildContext context) {
+    final fs = Theme.of(context).extension<FabledSwordTheme>()!;
+    final disabled = row.inLibrary || row.requested;
+    return Padding(
+      padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 10),
+      child: Row(children: [
+        ClipRRect(
+          borderRadius: BorderRadius.circular(6),
+          child: Container(
+            width: 56,
+            height: 56,
+            color: fs.slate,
+            child: row.imageUrl.isEmpty
+                ? Icon(Icons.album, color: fs.ash)
+                : Image.network(row.imageUrl, fit: BoxFit.cover,
+                    errorBuilder: (_, __, ___) =>
+                        Icon(Icons.album, color: fs.ash)),
+          ),
+        ),
+        const SizedBox(width: 12),
+        Expanded(
+          child: Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              Text(row.name,
+                  maxLines: 1,
+                  overflow: TextOverflow.ellipsis,
+                  style: TextStyle(color: fs.parchment, fontSize: 14)),
+              if (row.secondaryText.isNotEmpty)
+                Text(row.secondaryText,
+                    maxLines: 1,
+                    overflow: TextOverflow.ellipsis,
+                    style: TextStyle(color: fs.ash, fontSize: 12)),
+            ],
+          ),
+        ),
+        const SizedBox(width: 8),
+        if (row.inLibrary)
+          _Pill(label: 'In library', color: fs.ash)
+        else if (row.requested)
+          _Pill(label: 'Requested', color: fs.ash)
+        else
+          FilledButton(
+            onPressed: disabled ? null : onRequest,
+            style: FilledButton.styleFrom(
+              backgroundColor: fs.accent,
+              foregroundColor: fs.parchment,
+            ),
+            child: const Text('Request'),
+          ),
+      ]),
+    );
+  }
+}
+
+class _Pill extends StatelessWidget {
+  const _Pill({required this.label, required this.color});
+  final String label;
+  final Color color;
+  @override
+  Widget build(BuildContext context) {
+    final fs = Theme.of(context).extension<FabledSwordTheme>()!;
+    return Container(
+      padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 4),
+      decoration: BoxDecoration(
+        color: fs.iron,
+        borderRadius: BorderRadius.circular(4),
+      ),
+      child: Text(label, style: TextStyle(color: color, fontSize: 11)),
+    );
+  }
+}

flutter_client/lib/library/home_screen.dart

@@ -44,6 +44,11 @@ class HomeScreen extends ConsumerWidget {
             tooltip: 'Search',
             onPressed: () => context.push('/search'),
           ),
+          IconButton(
+            icon: Icon(Icons.explore, color: fs.parchment),
+            tooltip: 'Discover',
+            onPressed: () => context.push('/discover'),
+          ),
           IconButton(
             icon: Icon(Icons.settings, color: fs.parchment),
             tooltip: 'Settings',

flutter_client/lib/models/lidarr.dart

@@ -0,0 +1,47 @@
+/// Mirrors web/src/lib/api/types.ts LidarrSearchResult — one row in
+/// `/api/lidarr/search` results. `in_library` and `requested` let the
+/// UI gray out rows the user can't act on (already imported / already
+/// awaiting review).
+class LidarrSearchResult {
+  const LidarrSearchResult({
+    required this.mbid,
+    required this.name,
+    required this.secondaryText,
+    required this.imageUrl,
+    required this.artistMbid,
+    required this.albumMbid,
+    required this.inLibrary,
+    required this.requested,
+  });
+
+  final String mbid;
+  final String name;
+  final String secondaryText;
+  final String imageUrl;
+  final String artistMbid;
+  final String albumMbid;
+  final bool inLibrary;
+  final bool requested;
+
+  factory LidarrSearchResult.fromJson(Map<String, dynamic> j) =>
+      LidarrSearchResult(
+        mbid: j['mbid'] as String? ?? '',
+        name: j['name'] as String? ?? '',
+        secondaryText: j['secondary_text'] as String? ?? '',
+        imageUrl: j['image_url'] as String? ?? '',
+        artistMbid: j['artist_mbid'] as String? ?? '',
+        albumMbid: j['album_mbid'] as String? ?? '',
+        inLibrary: j['in_library'] as bool? ?? false,
+        requested: j['requested'] as bool? ?? false,
+      );
+}
+
+enum LidarrRequestKind { artist, album, track }
+
+extension LidarrRequestKindStr on LidarrRequestKind {
+  String get wire => switch (this) {
+        LidarrRequestKind.artist => 'artist',
+        LidarrRequestKind.album => 'album',
+        LidarrRequestKind.track => 'track',
+      };
+}

flutter_client/lib/shared/routing.dart

@@ -7,6 +7,7 @@ import '../auth/login_screen.dart';
 import '../auth/server_url_screen.dart';
 import '../library/album_detail_screen.dart';
 import '../library/artist_detail_screen.dart';
+import '../discover/discover_screen.dart';
 import '../library/home_screen.dart';
 import '../library/library_screen.dart';
 import '../player/now_playing_screen.dart';
@@ -60,6 +61,7 @@ GoRouter buildRouter(Ref ref) {
           GoRoute(path: '/queue', builder: (_, __) => const QueueScreen()),
           GoRoute(path: '/search', builder: (_, __) => const SearchScreen()),
           GoRoute(path: '/library', builder: (_, __) => const LibraryScreen()),
+          GoRoute(path: '/discover', builder: (_, __) => const DiscoverScreen()),
           GoRoute(path: '/settings', builder: (_, __) => const SettingsScreen()),
           GoRoute(path: '/playlists', builder: (_, __) => const PlaylistsListScreen()),
           GoRoute(