📋 Feature: Playlisten-Sync vom Navidrome-Server (Phase 2, Part 6/X)

- getPlaylists() + getPlaylistSongs() APIs für Subsonic-Playlist-Laden
- syncPlaylistsFromServer() in PlaylistService importiert alle Server-Playlisten als lokale
- Benennung mit 🌐 Präfix um Server-Playlisten zu kennzeichnen
- Settings-Button lädt alle Playlisten mit ihren Songs vom Server
- Zeigt Anzahl importierter Playlisten mit SnackBar

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XJzQjUtnvYUtHdnTs3iCru

lib/services/navidrome_service.dart

@@ -341,6 +341,56 @@ class NavidromeService {
       return null;
     }
   }
+
+  /// Lädt alle Playlisten vom Server.
+  Future<List<SubsonicPlaylist>> getPlaylists() async {
+    if (!istVerbunden) return [];
+    try {
+      final uri = _uri('getPlaylists.view');
+      final response = await http.get(uri).timeout(const Duration(seconds: 10));
+      if (response.statusCode != 200) return [];
+
+      final json = jsonDecode(response.body) as Map<String, dynamic>;
+      final subsonicResponse = json['subsonic-response'] as Map<String, dynamic>?;
+      if (subsonicResponse == null) return [];
+
+      final playlists = subsonicResponse['playlists'] as List<dynamic>?;
+      if (playlists == null) return [];
+
+      return playlists
+          .cast<Map<String, dynamic>>()
+          .map(SubsonicPlaylist.fromJson)
+          .toList();
+    } catch (e) {
+      debugPrint('getPlaylists Fehler: $e');
+      return [];
+    }
+  }
+
+  /// Lädt alle Songs einer Playlist vom Server.
+  Future<List<SubsonicSong>> getPlaylistSongs(String playlistId) async {
+    if (!istVerbunden) return [];
+    try {
+      final uri = _uri('getPlaylist.view', {'id': playlistId});
+      final response = await http.get(uri).timeout(const Duration(seconds: 10));
+      if (response.statusCode != 200) return [];
+
+      final json = jsonDecode(response.body) as Map<String, dynamic>;
+      final subsonicResponse = json['subsonic-response'] as Map<String, dynamic>?;
+      if (subsonicResponse == null) return [];
+
+      final playlist = subsonicResponse['playlist'] as Map<String, dynamic>?;
+      if (playlist == null) return [];
+
+      final songs = playlist['entry'] as List<dynamic>?;
+      if (songs == null) return [];
+
+      return songs.cast<Map<String, dynamic>>().map(SubsonicSong.fromJson).toList();
+    } catch (e) {
+      debugPrint('getPlaylistSongs Fehler: $e');
+      return [];
+    }
+  }
 }
 
 class SubsonicArtist {
@@ -358,6 +408,27 @@ class SubsonicArtist {
   );
 }
 
+class SubsonicPlaylist {
+  final String id;
+  final String name;
+  final String? comment;
+  final int songCount;
+
+  const SubsonicPlaylist({
+    required this.id,
+    required this.name,
+    this.comment,
+    this.songCount = 0,
+  });
+
+  factory SubsonicPlaylist.fromJson(Map<String, dynamic> j) => SubsonicPlaylist(
+    id: j['id'] as String,
+    name: j['name'] as String? ?? 'Unbekannt',
+    comment: j['comment'] as String?,
+    songCount: (j['songCount'] as int?) ?? 0,
+  );
+}
+
 class Lyrics {
   final String? text;
   final bool isEmpty;