Fix black screen bug when Material You theme enabled (#37)

Override Material You ColorScheme backgrounds with app's preferred colors.
Material You generates unpredictable background values that could cause
black screen or inconsistent navigation bar colors.

- Force dark background to 0xFF1a1a1a
- Force dark surface to 0xFF2a2a2a
- Force light background to 0xFFFAFAFA

Bump version to 2.8.3-beta+40

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/main.dart

@@ -229,10 +229,17 @@ class _MusicAssistantAppState extends State<MusicAssistantApp> with WidgetsBindi
               ColorScheme? darkColorScheme;
 
               if (themeProvider.useMaterialTheme && snapshot.hasData && snapshot.data != null) {
-                // Use system color schemes
+                // Use system color schemes, but override background to match app design
+                // Material You doesn't set background consistently, causing black screen issues
                 final (light, dark) = snapshot.data!;
-                lightColorScheme = light;
-                darkColorScheme = dark;
+                lightColorScheme = light.copyWith(
+                  surface: light.surface,
+                  background: const Color(0xFFFAFAFA), // App's preferred light background
+                );
+                darkColorScheme = dark.copyWith(
+                  surface: const Color(0xFF2a2a2a), // App's preferred dark surface
+                  background: const Color(0xFF1a1a1a), // App's preferred dark background
+                );
               } else {
                 // Use custom color from theme provider
                 lightColorScheme = generateLightColorScheme(themeProvider.customColor);

pubspec.yaml

@@ -1,7 +1,7 @@
 name: ensemble
 description: A minimalistic Music Assistant client built with Flutter
 publish_to: 'none'
-version: 2.8.2-beta+39
+version: 2.8.3-beta+40
 
 environment:
   sdk: '>=3.0.0 <4.0.0'