feat(flutter/player): mini PlayerBar in shell + tap-to-play wiring

PlayerBar reads playbackState + mediaItem streams; hidden when no
queue. Home track-row tap, album play button, album track tap, artist
play button (shuffle) all route to playerActions.playTracks. Token +
baseUrl forwarded to the audio handler before each new queue.

flutter_client/lib/library/album_detail_screen.dart

@@ -3,6 +3,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../api/endpoints/likes.dart';
 import '../likes/like_button.dart';
+import '../player/player_provider.dart';
 import '../theme/theme_extension.dart';
 import 'library_providers.dart';
 import 'widgets/track_row.dart';
@@ -42,7 +43,7 @@ class AlbumDetailScreen extends ConsumerWidget {
                     decoration: BoxDecoration(color: fs.accent, shape: BoxShape.circle),
                     child: IconButton(
                       icon: Icon(Icons.play_arrow, color: fs.parchment),
-                      onPressed: () { /* play wired in Task 18 */ },
+                      onPressed: () => ref.read(playerActionsProvider).playTracks(r.tracks),
                     ),
                   ),
                   LikeButton(kind: LikeKind.album, id: r.album.id, size: 28),
@@ -51,7 +52,10 @@ class AlbumDetailScreen extends ConsumerWidget {
               for (final t in r.tracks)
                 TrackRow(
                   track: t,
-                  onTap: () { /* play wired in Task 18 */ },
+                  onTap: () {
+                    final start = r.tracks.indexOf(t);
+                    ref.read(playerActionsProvider).playTracks(r.tracks, initialIndex: start);
+                  },
                   trailing: LikeButton(kind: LikeKind.track, id: t.id),
                 ),
             ]),

flutter_client/lib/library/artist_detail_screen.dart

@@ -5,6 +5,7 @@ import 'package:go_router/go_router.dart';
 import '../api/endpoints/likes.dart';
 import '../likes/like_button.dart';
 import '../models/album.dart';
+import '../player/player_provider.dart';
 import '../theme/theme_extension.dart';
 import 'library_providers.dart';
 import 'widgets/album_card.dart';
@@ -49,7 +50,12 @@ class ArtistDetailScreen extends ConsumerWidget {
                 decoration: BoxDecoration(color: fs.accent, shape: BoxShape.circle),
                 child: IconButton(
                   icon: Icon(Icons.play_arrow, color: fs.parchment),
-                  onPressed: () { /* play wired in Task 18 */ },
+                  onPressed: () async {
+                    final tracks = await ref.read(artistTracksProvider(id).future);
+                    if (tracks.isEmpty) return;
+                    final shuffled = [...tracks]..shuffle();
+                    ref.read(playerActionsProvider).playTracks(shuffled);
+                  },
                 ),
               ),
               LikeButton(kind: LikeKind.artist, id: a.id, size: 28),

flutter_client/lib/library/home_screen.dart

@@ -5,6 +5,7 @@ import 'package:go_router/go_router.dart';
 import '../models/album.dart';
 import '../models/artist.dart';
 import '../models/track.dart';
+import '../player/player_provider.dart';
 import '../theme/theme_extension.dart';
 import 'library_providers.dart';
 import 'widgets/album_card.dart';
@@ -66,7 +67,10 @@ class HomeScreen extends ConsumerWidget {
           for (final t in tracks)
             SizedBox(
               width: 280,
-              child: TrackRow(track: t, onTap: () { /* play wired in Task 18 */ }),
+              child: TrackRow(
+                track: t,
+                onTap: () => ref.read(playerActionsProvider).playTracks([t]),
+              ),
             ),
         ],
       );

flutter_client/lib/player/player_bar.dart

@@ -0,0 +1,53 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:go_router/go_router.dart';
+
+import '../theme/theme_extension.dart';
+import 'player_provider.dart';
+
+class PlayerBar extends ConsumerWidget {
+  const PlayerBar({super.key});
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final fs = Theme.of(context).extension<FabledSwordTheme>()!;
+    final mediaItem = ref.watch(mediaItemProvider).valueOrNull;
+    final playback = ref.watch(playbackStateProvider).valueOrNull;
+    if (mediaItem == null) return const SizedBox.shrink();
+
+    return Material(
+      color: fs.iron,
+      child: InkWell(
+        onTap: () => context.push('/now-playing'),
+        child: Padding(
+          padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
+          child: Row(children: [
+            Container(width: 48, height: 48, color: fs.slate),
+            const SizedBox(width: 12),
+            Expanded(child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: [
+                Text(mediaItem.title, maxLines: 1, overflow: TextOverflow.ellipsis,
+                    style: TextStyle(color: fs.parchment, fontSize: 14)),
+                Text(mediaItem.artist ?? '', maxLines: 1, overflow: TextOverflow.ellipsis,
+                    style: TextStyle(color: fs.ash, fontSize: 12)),
+              ],
+            )),
+            IconButton(
+              icon: Icon(playback?.playing == true ? Icons.pause : Icons.play_arrow, color: fs.parchment),
+              onPressed: () {
+                final h = ref.read(audioHandlerProvider);
+                if (playback?.playing == true) { h.pause(); } else { h.play(); }
+              },
+            ),
+            IconButton(
+              icon: Icon(Icons.skip_next, color: fs.parchment),
+              onPressed: () => ref.read(audioHandlerProvider).skipToNext(),
+            ),
+          ]),
+        ),
+      ),
+    );
+  }
+}

flutter_client/lib/shared/routing.dart

@@ -8,6 +8,7 @@ import '../auth/server_url_screen.dart';
 import '../library/album_detail_screen.dart';
 import '../library/artist_detail_screen.dart';
 import '../library/home_screen.dart';
+import '../player/player_bar.dart';
 import 'widgets/version_gate.dart';
 
 GoRouter buildRouter(Ref ref) {
@@ -53,10 +54,10 @@ class _ShellWithPlayerBar extends StatelessWidget {
   final Widget child;
   @override
   Widget build(BuildContext context) {
-    // PlayerBar is wired in Task 18; this placeholder leaves the shell slot.
     return Column(
       children: [
         Expanded(child: child),
+        const PlayerBar(),
       ],
     );
   }