Merge: Fix Server-Bibliothek-Laden + Tab-Abschnitt

# Conflicts:
#	CHANGELOG.md

lib/services/navidrome_service.dart

@@ -58,6 +58,16 @@ class SubsonicAlbum {
   );
 }
 
+/// Fehler einer Subsonic-Antwort mit `status:"failed"` (Navidrome liefert
+/// dafür HTTP 200). Trägt die Server-Meldung, damit die UI sie zeigen kann.
+class NavidromeException implements Exception {
+  final String message;
+  final int? code;
+  NavidromeException(this.message, {this.code});
+  @override
+  String toString() => 'NavidromeException(${code ?? '-'}): $message';
+}
+
 class NavidromeService {
   final FlutterSecureStorage _secure = const FlutterSecureStorage();
 
@@ -123,6 +133,35 @@ class NavidromeService {
 
   bool get istVerbunden => _serverUrl.isNotEmpty && _user.isNotEmpty;
 
+  /// Dekodiert eine Subsonic-JSON-Antwort und wirft [NavidromeException],
+  /// wenn der Server `status:"failed"` meldet (z. B. falsches Passwort) —
+  /// solche Antworten kommen mit HTTP 200 und dürfen nicht als „leer" gelten.
+  @visibleForTesting
+  static Map<String, dynamic> parseSubsonic(String body) {
+    final data = jsonDecode(body) as Map<String, dynamic>;
+    final resp = data['subsonic-response'] as Map<String, dynamic>?;
+    if (resp == null) {
+      throw NavidromeException('Ungültige Server-Antwort (kein subsonic-response)');
+    }
+    if (resp['status'] == 'failed') {
+      final err = resp['error'] as Map<String, dynamic>?;
+      throw NavidromeException(
+        (err?['message'] as String?) ?? 'Unbekannter Server-Fehler',
+        code: err?['code'] as int?,
+      );
+    }
+    return resp;
+  }
+
+  /// Liest Alben aus einer geprüften `getAlbumList2`-Antwort (ID3-basiert).
+  @visibleForTesting
+  static List<SubsonicAlbum> parseAlben(Map<String, dynamic> resp) {
+    final list = resp['albumList2']?['album'] as List? ?? [];
+    return list
+        .map((j) => SubsonicAlbum.fromJson(j as Map<String, dynamic>))
+        .toList();
+  }
+
   Uri _uri(String endpoint, [Map<String, String>? extra]) {
     if (_token == null || _token!.isEmpty) {
       throw StateError('Navidrome ist nicht verbunden. Bitte zuerst Zugangsdaten setzen.');
@@ -142,13 +181,18 @@ class NavidromeService {
   Future<bool> ping() async {
     try {
       final r = await http.get(_uri('ping.view')).timeout(const Duration(seconds: 10));
-      if (r.statusCode == 200) {
-        logger.info('✅ Navidrome Verbindung erfolgreich: $_serverUrl');
-        return true;
-      } else {
+      if (r.statusCode != 200) {
         logger.warning('Navidrome Ping fehlgeschlagen (HTTP ${r.statusCode}): $_serverUrl');
         return false;
       }
+      // Subsonic liefert auch bei falschem Passwort HTTP 200 → Body prüfen,
+      // sonst meldet der Login fälschlich Erfolg (status:"failed").
+      parseSubsonic(r.body);
+      logger.info('✅ Navidrome Verbindung erfolgreich: $_serverUrl');
+      return true;
+    } on NavidromeException catch (e) {
+      logger.warning('Navidrome Login abgelehnt: ${e.message}');
+      return false;
     } catch (e) {
       // Details für die Diagnose: ohne URL/Exception-Typ ist im Log nicht
       // erkennbar, ob DNS, IPv6, TLS oder eine falsche URL die Ursache ist.
@@ -181,14 +225,16 @@ class NavidromeService {
 
   Future<List<SubsonicAlbum>> getAlben({int anzahl = 50}) async {
     try {
-      final r = await http.get(_uri('getAlbumList.view', {'type': 'newest', 'size': '$anzahl'})).timeout(const Duration(seconds: 15));
-      if (r.statusCode != 200) return [];
-      final data = jsonDecode(r.body);
-      final list = data['subsonic-response']?['albumList']?['album'] as List? ?? [];
-      return list.map((j) => SubsonicAlbum.fromJson(j)).toList();
+      // getAlbumList2 = ID3-basiert (wie getArtists) — der Folder-Endpoint
+      // getAlbumList liefert bei tag-organisierten Navidrome-Libraries leer.
+      final r = await http
+          .get(_uri('getAlbumList2.view', {'type': 'newest', 'size': '$anzahl'}))
+          .timeout(const Duration(seconds: 15));
+      if (r.statusCode != 200) throw NavidromeException('HTTP ${r.statusCode}');
+      return parseAlben(parseSubsonic(r.body));
     } catch (e) {
       await logger.error('Navidrome getAlben Fehler: $e', e, StackTrace.current);
-      return [];
+      rethrow;
     }
   }
 
@@ -249,20 +295,20 @@ class NavidromeService {
   Future<List<SubsonicArtist>> getArtists() async {
     try {
       final r = await http.get(_uri('getArtists.view')).timeout(const Duration(seconds: 15));
-      if (r.statusCode != 200) return [];
-      final data = jsonDecode(r.body);
-      final indexData = data['subsonic-response']?['artists']?['index'] as List? ?? [];
+      if (r.statusCode != 200) throw NavidromeException('HTTP ${r.statusCode}');
+      final resp = parseSubsonic(r.body);
+      final indexData = resp['artists']?['index'] as List? ?? [];
       final artists = <SubsonicArtist>[];
       for (final idx in indexData) {
         final artistList = idx['artist'] as List? ?? [];
         for (final a in artistList) {
-          artists.add(SubsonicArtist.fromJson(a));
+          artists.add(SubsonicArtist.fromJson(a as Map<String, dynamic>));
         }
       }
       return artists;
     } catch (e) {
       await logger.error('Navidrome getArtists Fehler: $e', e, StackTrace.current);
-      return [];
+      rethrow;
     }
   }