Fix mobile app submodule initialization and cleanup

- Removed incorrect swingmusic_mobile directory
- Properly initialized swingmusic_mobile submodule from swingmusic-mobile.git
- Clean submodule configuration for unified release workflow

swingmusic_mobile/pubspec.yaml

@@ -1,69 +0,0 @@
-name: swingmusic_mobile
-description: "SwingMusic Mobile - Flutter cross-platform music player"
-
-publish_to: 'none'
-
-version: 1.0.0+1
-
-environment:
-  sdk: ^3.10.4
-
-dependencies:
-  flutter:
-    sdk: flutter
-  flutter_localizations:
-    sdk: flutter
-  provider: ^6.1.1
-  go_router: ^12.1.3
-  just_audio: ^0.9.46
-  audio_session: ^0.1.25
-  permission_handler: ^11.4.0
-  path_provider: ^2.1.1
-  shared_preferences: ^2.2.2
-  dio: ^5.3.2
-  retrofit: ^4.0.1
-  json_annotation: ^4.8.1
-  lottie: ^2.7.0
-  hive_flutter: ^1.1.0
-  
-  # Media & Metadata
-  flutter_media_metadata: ^1.0.0
-  
-  # Visualizations
-  flutter_audio_waveforms: ^1.2.0
-  
-  # Background Processing
-  workmanager: ^0.5.2
-  
-  # UI Components
-  cupertino_icons: ^1.0.8
-  
-  # Additional Utilities
-  equatable: ^2.0.5
-  uuid: ^4.2.1
-  intl: ^0.20.2
-
-dev_dependencies:
-  flutter_test:
-    sdk: flutter
-
-  # Linting
-  flutter_lints: ^6.0.0
-  
-  # Code Generation
-  retrofit_generator: ^7.0.8
-  json_serializable: ^6.7.1
-  hive_generator: ^2.0.1
-  build_runner: ^2.4.7
-
-# For information on the generic Dart part of this file, see the
-# following page: https://dart.dev/tools/pub/pubspec
-
-# The following section is specific to Flutter packages.
-flutter:
-
-  uses-material-design: true
-
-  assets:
-    - assets/images/
-    - assets/audio/