perf: optimize state management, add HTTPS validation, improve UI performance

- Add HTTPS-only validation for APK downloads and update checks
- Use .select() for Riverpod providers to prevent unnecessary rebuilds
- Add keys to all list builders for efficient updates
- Implement request cancellation for outdated API requests
- Debounce all network requests (URLs and searches)
- Limit file existence cache to 500 entries
- Add ref.onDispose for timer cleanup
- Add error handling for share intent stream
- Redesign About page with Material Expressive 3 style
- Rename Search tab to Home
- Remove Features section from README

lib/theme/dynamic_color_wrapper.dart

@@ -27,7 +27,6 @@ class DynamicColorWrapper extends ConsumerWidget {
           // Use dynamic colors from wallpaper (Android 12+)
           lightScheme = lightDynamic;
           darkScheme = darkDynamic;
-          debugPrint('Using dynamic color from wallpaper');
         } else {
           // Fallback to seed color
           final seedColor = themeSettings.seedColor;
@@ -39,7 +38,6 @@ class DynamicColorWrapper extends ConsumerWidget {
             seedColor: seedColor,
             brightness: Brightness.dark,
           );
-          debugPrint('Using fallback seed color: ${seedColor.toARGB32().toRadixString(16)}');
         }
 
         // Build themes