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/api/endpoints/likes.dart

@@ -1,5 +1,10 @@
 import 'package:dio/dio.dart';
 
+import '../../models/album.dart';
+import '../../models/artist.dart';
+import '../../models/page.dart';
+import '../../models/track.dart';
+
 enum LikeKind { artist, album, track }
 
 extension LikeKindPath on LikeKind {
@@ -22,6 +27,31 @@ class LikesApi {
     await _dio.delete<void>('/api/likes/${kind.path}/$id');
   }
 
+  /// GET /api/likes/tracks?limit=N&offset=N. Paged.
+  Future<Paged<TrackRef>> listTracks({int limit = 50, int offset = 0}) async {
+    final r = await _dio.get<Map<String, dynamic>>(
+      '/api/likes/tracks',
+      queryParameters: {'limit': limit, 'offset': offset},
+    );
+    return Paged.fromJson(r.data ?? const {}, TrackRef.fromJson);
+  }
+
+  Future<Paged<AlbumRef>> listAlbums({int limit = 50, int offset = 0}) async {
+    final r = await _dio.get<Map<String, dynamic>>(
+      '/api/likes/albums',
+      queryParameters: {'limit': limit, 'offset': offset},
+    );
+    return Paged.fromJson(r.data ?? const {}, AlbumRef.fromJson);
+  }
+
+  Future<Paged<ArtistRef>> listArtists({int limit = 50, int offset = 0}) async {
+    final r = await _dio.get<Map<String, dynamic>>(
+      '/api/likes/artists',
+      queryParameters: {'limit': limit, 'offset': offset},
+    );
+    return Paged.fromJson(r.data ?? const {}, ArtistRef.fromJson);
+  }
+
   /// Returns sets of {artists, albums, tracks} the user has liked.
   /// Server response keys (verified in internal/api/likes.go
   /// `likedIDsResponse`): `artist_ids`, `album_ids`, `track_ids`.