refactor: enhance theme and error handling across the application

- Updated error handling in EnhancedErrorService to utilize context for color tokens, improving theme consistency.
- Refactored various components to use context-aware shadow and color properties, enhancing visual coherence.
- Replaced hardcoded color values with dynamic tokens in multiple widgets, ensuring better adaptability to theme changes.
- Improved overall code maintainability by centralizing theme-related logic and reducing direct dependencies on static theme values.

lib/core/providers/app_startup_providers.dart

@@ -535,7 +535,7 @@ Future<void> _maybeShowOnboarding(Ref ref) async {
             borderRadius: const BorderRadius.vertical(
               top: Radius.circular(AppBorderRadius.modal),
             ),
-            boxShadow: ConduitShadows.modal,
+            boxShadow: ConduitShadows.modal(context),
           ),
           child: const OnboardingSheet(),
         ),