chore(deps): update Flutter and Go dependencies to latest stable

Flutter: bump connectivity_plus, device_info_plus, share_plus, receive_sharing_intent, path_provider, flutter_local_notifications to latest stable. Revert file_picker from 12.0.0-beta to 11.0.2 stable and migrate pickFile (singular) to pickFiles. Add win32 ^6.0.1 dependency_overrides to resolve the win32 5 vs 6 conflict between file_picker stable and device_info_plus (Windows-desktop-only transitive dep, not used on mobile targets). Go: update goja, golang.org/x/mobile, golang.org/x/tools, regexp2/v2 to latest.

lib/screens/library_playlists_screen.dart

@@ -361,8 +361,9 @@ class LibraryPlaylistsScreen extends ConsumerWidget {
     WidgetRef ref,
     String playlistId,
   ) async {
-    final picked = await FilePicker.pickFile(type: FileType.image);
-    if (picked == null) return;
+    final result = await FilePicker.pickFiles(type: FileType.image);
+    if (result == null || result.files.isEmpty) return;
+    final picked = result.files.first;
 
     final path = picked.path;
     if (path == null || path.isEmpty) return;

lib/screens/library_tracks_folder_screen.dart

@@ -571,8 +571,9 @@ class _LibraryTracksFolderScreenState
     final playlistId = widget.playlistId;
     if (playlistId == null) return;
 
-    final picked = await FilePicker.pickFile(type: FileType.image);
-    if (picked == null) return;
+    final result = await FilePicker.pickFiles(type: FileType.image);
+    if (result == null || result.files.isEmpty) return;
+    final picked = result.files.first;
 
     final path = picked.path;
     if (path == null || path.isEmpty) return;

lib/screens/track_metadata_edit_sheet.dart

@@ -201,15 +201,19 @@ class _EditMetadataSheetState extends State<_EditMetadataSheet> {
 
   Future<void> _pickCoverImage() async {
     try {
-      final picked = await FilePicker.pickFile(type: FileType.image);
-      if (picked == null) return;
+      final result = await FilePicker.pickFiles(
+        type: FileType.image,
+        withData: true,
+      );
+      if (result == null || result.files.isEmpty) return;
+      final picked = result.files.first;
 
       final sourcePath = picked.path;
       Uint8List? bytes;
       final needsByteFallback =
           !_hasValue(sourcePath) && !_hasValue(picked.extension);
       if (needsByteFallback) {
-        bytes = await picked.readAsBytes();
+        bytes = picked.bytes;
       }
       final extension = _resolveImageExtension(picked.extension, bytes);