Restructure step 4: local library and media identity

- L1 (core, offline): release names with kinds (episode, movie, extra:
  OP/ED/Opening/Ending/NC/PV/OVA…), folder hints (season and name from
  parentheticals, ranges), one show across folders, gaps and next with
  skipped numbers, junk ignored, stable keys.
- L2 (app, device-owned cache): AniList match with synonyms and
  sequel walking, episode mapping across cours (AnimeFlow runs when
  signed in), art and episode titles, "Wrong show?" pins per show or
  folder, episode offsets; lazy, spaced requests, works offline.
- Files tab as a library: poster cards, show pages with banner, gap
  prompt, extras, movies, Wrong show? and Episode numbers.
- media.ref produced for local files, Jellyfin (provider ids) and links,
  carried in swaps and Up next; receivers name media from it.
- Hosting relays each Jellyfin item through its own server's login.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/desktop/lib/src/state/server_isolate.dart

@@ -159,9 +159,10 @@ class ServerIsolate {
 
   /// Opens the server to the network ([SyncServer.share]): a listener on
   /// every interface at [port], the password [secret], the Jellyfin relay
-  /// login [jellyfin]. Returns the bound port; throws a [StateError] with
+  /// logins [jellyfin] (one per Jellyfin server). Returns the bound port;
+  /// throws a [StateError] with
   /// the server's reason (a port in use) when it cannot.
-  Future<int> share({required int port, required String secret, JellyfinCredential? jellyfin,
+  Future<int> share({required int port, required String secret, List<JellyfinCredential>? jellyfin,
       Duration timeout = const Duration(seconds: 10)}) async {
     if (_exited.isCompleted) throw StateError('the server is not running');
     final reply = ReceivePort('server share');
@@ -170,7 +171,7 @@ class ServerIsolate {
         't': 'share',
         'port': port,
         'secret': secret,
-        'jellyfin': ?jellyfin?.toMap(),
+        if (jellyfin != null) 'jellyfin': [for (final c in jellyfin) c.toMap()],
         'reply': reply.sendPort,
       });
       final msg = await reply.first.timeout(timeout);