feat(ui): add Mornye glass theme and adaptive music player

Add a selectable Mornye theme with shared glass controls, dialogs, sheets, notifications, and collection headers while retaining Material components.

Update player artwork, lyrics transitions and highlighting, synchronized rolling time labels, volume controls, and compact navigation. Unify metadata, Library, search, and extension surfaces; preserve restored artwork and report extension load failures.

Validation: full Flutter analyzer clean; 713 tests passed and 4 skipped; pinned Dart formatting and diff checks passed; signed ARM64 and ARM32 release APKs built and verified.

lib/widgets/audio_analysis_spectrogram.dart

@@ -28,7 +28,8 @@ class _SpectrogramView extends StatelessWidget {
     final cs = Theme.of(context).colorScheme;
     const labelColor = Color(0xFFB5B5B5);
 
-    return Card(
+    final card = AppContentCard(
+      preserveColor: true,
       color: Colors.black,
       clipBehavior: Clip.antiAlias,
       child: Column(
@@ -41,7 +42,8 @@ class _SpectrogramView extends StatelessWidget {
                 scrollDirection: Axis.horizontal,
                 child: Row(
                   children: [
-                    ChoiceChip(
+                    AppChoiceChip(
+                      singleChoice: true,
                       label: Text(context.l10n.audioAnalysisChannels),
                       selected: selectedChannel < 0,
                       onSelected: channelLoading
@@ -51,7 +53,8 @@ class _SpectrogramView extends StatelessWidget {
                     ),
                     for (var channel = 0; channel < channels; channel++) ...[
                       const SizedBox(width: 6),
-                      ChoiceChip(
+                      AppChoiceChip(
+                        singleChoice: true,
                         label: Text('Ch ${channel + 1}'),
                         selected: selectedChannel == channel,
                         onSelected: channelLoading
@@ -141,6 +144,11 @@ class _SpectrogramView extends StatelessWidget {
         ],
       ),
     );
+    // The plot stays black in both appearances; its controls need matching
+    // contrast even when the surrounding Mornye page uses the light theme.
+    return context.isMornye
+        ? Theme(data: MornyeTheme.build(Brightness.dark), child: card)
+        : card;
   }
 
   static List<Color> _legendColors() {