feat(flutter): library screen with 5 tabs (Artists/Albums/History/Liked/Hidden)

Models:
- history_event.dart (HistoryEvent + HistoryPage envelope)
- quarantine_mine.dart (QuarantineMineRow for /api/quarantine/mine)
- Renamed Page<T> -> Paged<T> to avoid collision with Material's Page

Endpoints:
- library_lists.dart: listArtists / listAlbums (paged)
- me.dart: history + quarantineMine
- likes.dart: extended with listTracks/Albums/Artists (paged)

UI:
- library_screen.dart: TabBar over 5 tabs
- Artists tab: 3-col grid
- Albums tab: 2-col grid
- History tab: list with relative-time formatting (matches HistoryRow.svelte)
- Liked tab: 3 stacked sections (artists scroll-row, albums scroll-row, tracks list)
- Hidden tab: list of quarantined tracks with reason pill
- /library route + library_music icon on home AppBar

First page only for v1 (limit 50). Infinite scroll deferred.

flutter_client/lib/models/quarantine_mine.dart

@@ -0,0 +1,46 @@
+/// Mirrors web/src/lib/api/types.ts LidarrQuarantineMineRow. One row
+/// per quarantined track owned by the caller. Server returns a flat
+/// list (no Page envelope) at /api/quarantine/mine.
+class QuarantineMineRow {
+  const QuarantineMineRow({
+    required this.trackId,
+    required this.reason,
+    this.notes,
+    required this.createdAt,
+    required this.trackTitle,
+    required this.trackDurationMs,
+    required this.albumId,
+    required this.albumTitle,
+    this.albumCoverArtPath,
+    required this.artistId,
+    required this.artistName,
+  });
+
+  final String trackId;
+  /// One of: bad_rip / wrong_file / wrong_tags / duplicate / other.
+  final String reason;
+  final String? notes;
+  final String createdAt;
+  final String trackTitle;
+  final int trackDurationMs;
+  final String albumId;
+  final String albumTitle;
+  final String? albumCoverArtPath;
+  final String artistId;
+  final String artistName;
+
+  factory QuarantineMineRow.fromJson(Map<String, dynamic> j) =>
+      QuarantineMineRow(
+        trackId: j['track_id'] as String? ?? '',
+        reason: j['reason'] as String? ?? 'other',
+        notes: j['notes'] as String?,
+        createdAt: j['created_at'] as String? ?? '',
+        trackTitle: j['track_title'] as String? ?? '',
+        trackDurationMs: (j['track_duration_ms'] as num?)?.toInt() ?? 0,
+        albumId: j['album_id'] as String? ?? '',
+        albumTitle: j['album_title'] as String? ?? '',
+        albumCoverArtPath: j['album_cover_art_path'] as String?,
+        artistId: j['artist_id'] as String? ?? '',
+        artistName: j['artist_name'] as String? ?? '',
+      );
+}