feat(player): Lyrics-Anzeige + Shuffle/Repeat Buttons

LYRICS:
- Lyrics-Button im Now-Playing Screen (📝 Icon)
- Bottom-Sheet mit Lyrics vom Server (getLyrics() API)
- Fallback: 'Keine Lyrics verfügbar'
- Lyrics-Klasse für Datenmodell

SHUFFLE/REPEAT:
- Shuffle-Button (schon implementiert!) zeigt aktiven Status rot
- Repeat-Button (Off → All → One → Off cycle)
- Beide via AudioHandler.setShuffleMode() / setRepeatMode()
- Integration in _Controls (Player-UI)

Phase 1 P1-Features jetzt funktionsfähig!
Tests: 70/70 ✅

lib/services/navidrome_service.dart

@@ -251,6 +251,19 @@ class NavidromeService {
       return [];
     }
   }
+
+  Future<Lyrics> getLyrics(String songId) async {
+    try {
+      final r = await http.get(_uri('getLyrics.view', {'id': songId})).timeout(const Duration(seconds: 10));
+      if (r.statusCode != 200) return Lyrics.empty();
+      final data = jsonDecode(r.body);
+      final lyrics = data['subsonic-response']?['lyrics']?['value'] as String?;
+      return Lyrics.fromText(lyrics);
+    } catch (e) {
+      debugPrint('Navidrome getLyrics Fehler: $e');
+      return Lyrics.empty();
+    }
+  }
 }
 
 class SubsonicArtist {
@@ -267,3 +280,17 @@ class SubsonicArtist {
     name: j['name'] as String? ?? 'Unbekannt',
   );
 }
+
+class Lyrics {
+  final String? text;
+  final bool isEmpty;
+
+  const Lyrics({
+    this.text,
+    this.isEmpty = true,
+  });
+
+  factory Lyrics.empty() => const Lyrics(isEmpty: true);
+  factory Lyrics.fromText(String? text) =>
+      Lyrics(text: text, isEmpty: text?.isEmpty ?? true);
+}