feat: remove Tidal built-in provider, add extension download dedup/ISRC/Lyrics APIs, and expand l10n/a11y

Remove Tidal from built-in provider registry (metadata, search, download,
URL parsing) and delete tidal.go. Introduce extension runtime APIs for
lyrics lookup (getLyricsLRC), ISRC existence check (checkISRCExists), and
ISRC index management (addToISRCIndex). Refactor extension download response
construction into normalizeExtensionDownloadResult/overlayExtensionDownloadMetadata
helpers with AlreadyExists support and ISRC indexing. Switch download mirrors
to DoRequestWithUserAgent for ISP blocking detection. Add 50+ new
localization keys and accessibility labels across all supported locales.

lib/screens/queue_tab.dart

@@ -3537,7 +3537,7 @@ class _QueueTabState extends ConsumerState<QueueTab> {
                             prefixIcon: const Icon(Icons.search),
                             suffixIcon: _searchQuery.isNotEmpty
                                 ? IconButton(
-                                    tooltip: 'Clear',
+                                    tooltip: context.l10n.dialogClear,
                                     icon: const Icon(Icons.clear),
                                     onPressed: () {
                                       _searchController.clear();
@@ -3954,7 +3954,7 @@ class _QueueTabState extends ConsumerState<QueueTab> {
 
     return Semantics(
       button: true,
-      label: 'Open $title, $count ${count == 1 ? 'item' : 'items'}',
+      label: context.l10n.a11yOpenItemCount(title, count),
       child: GestureDetector(
         onTap: onTap,
         onLongPress: onLongPress,
@@ -4909,7 +4909,11 @@ class _QueueTabState extends ConsumerState<QueueTab> {
   }) {
     return Semantics(
       button: true,
-      label: 'Open album $albumName by $artistName, $trackCount tracks',
+      label: context.l10n.a11yOpenAlbumByArtistTrackCount(
+        albumName,
+        artistName,
+        trackCount,
+      ),
       child: GestureDetector(
         onTap: onTap,
         child: Column(
@@ -6444,7 +6448,7 @@ class _QueueTabState extends ConsumerState<QueueTab> {
           onPressed: () =>
               ref.read(downloadQueueProvider.notifier).cancelItem(item.id),
           icon: Icon(Icons.close, color: colorScheme.error),
-          tooltip: 'Cancel',
+          tooltip: context.l10n.dialogCancel,
           style: IconButton.styleFrom(
             backgroundColor: colorScheme.errorContainer.withValues(alpha: 0.3),
           ),
@@ -6454,14 +6458,14 @@ class _QueueTabState extends ConsumerState<QueueTab> {
           onPressed: () =>
               ref.read(downloadQueueProvider.notifier).cancelItem(item.id),
           icon: Icon(Icons.stop, color: colorScheme.error),
-          tooltip: 'Stop',
+          tooltip: context.l10n.actionStop,
           style: IconButton.styleFrom(
             backgroundColor: colorScheme.errorContainer.withValues(alpha: 0.3),
           ),
         );
       case DownloadStatus.finalizing:
         return Semantics(
-          label: 'Finalizing download',
+          label: context.l10n.queueFinalizingDownload,
           child: SizedBox(
             width: 40,
             height: 40,
@@ -6500,7 +6504,7 @@ class _QueueTabState extends ConsumerState<QueueTab> {
                       coverUrl: item.track.coverUrl ?? '',
                     ),
                     icon: Icon(Icons.play_arrow, color: colorScheme.primary),
-                    tooltip: 'Play',
+                    tooltip: context.l10n.tooltipPlay,
                     style: IconButton.styleFrom(
                       backgroundColor: colorScheme.primaryContainer.withValues(
                         alpha: 0.3,
@@ -6509,7 +6513,7 @@ class _QueueTabState extends ConsumerState<QueueTab> {
                   )
                 else
                   Semantics(
-                    label: 'Downloaded file missing',
+                    label: context.l10n.queueDownloadedFileMissing,
                     child: ExcludeSemantics(
                       child: Icon(
                         Icons.error_outline,
@@ -6520,7 +6524,7 @@ class _QueueTabState extends ConsumerState<QueueTab> {
                   ),
                 const SizedBox(width: 4),
                 Semantics(
-                  label: 'Download completed',
+                  label: context.l10n.queueDownloadCompleted,
                   child: ExcludeSemantics(
                     child: Container(
                       padding: const EdgeInsets.all(8),
@@ -6549,7 +6553,7 @@ class _QueueTabState extends ConsumerState<QueueTab> {
               onPressed: () =>
                   ref.read(downloadQueueProvider.notifier).retryItem(item.id),
               icon: Icon(Icons.refresh, color: colorScheme.primary),
-              tooltip: 'Retry',
+              tooltip: context.l10n.dialogRetry,
               style: IconButton.styleFrom(
                 backgroundColor: colorScheme.primaryContainer.withValues(
                   alpha: 0.3,
@@ -6566,7 +6570,7 @@ class _QueueTabState extends ConsumerState<QueueTab> {
                     ? colorScheme.error
                     : colorScheme.onSurfaceVariant,
               ),
-              tooltip: 'Remove',
+              tooltip: context.l10n.dialogRemove,
               style: item.status == DownloadStatus.failed
                   ? IconButton.styleFrom(
                       backgroundColor: colorScheme.errorContainer.withValues(
@@ -6743,7 +6747,10 @@ class _QueueTabState extends ConsumerState<QueueTab> {
         : colorScheme.onSecondaryContainer;
 
     return Semantics(
-      label: '${item.trackName} by ${item.artistName}',
+      label: context.l10n.a11yTrackByArtist(
+        item.trackName,
+        item.artistName,
+      ),
       selected: isSelected,
       child: Card(
         margin: const EdgeInsets.symmetric(horizontal: 16, vertical: 4),