Add search, offline queue, app icon, and UI polish

- Collapsible search in notes and tasks: magnifying glass in AppBar
  expands to a text field inline; close button resets the filter
- Offline capture queue: failed quick-captures (NetworkException) are
  persisted to SharedPreferences and retried automatically on next
  successful submit or app start; badge shows pending count
- App icon: book-with-sparkle logo from FabledAssistant SVG rendered
  at all Android densities with adaptive icon (indigo #6366f1 bg)
- Dark mode subtitle fix: use colorScheme.onSurfaceVariant for note
  preview and conversation timestamp text
- Remove swipe-to-delete (accidental deletions); long-press remains
- Chat: SSE streaming reliability, polling fallback, title patching
- Settings: theme toggle (system/light/dark) persisted to prefs
- Notes: delete button in edit screen; body preview in list
- Tasks: fix delete dialog context; description search support

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/providers/api_client_provider.dart

@@ -6,6 +6,7 @@ import '../data/api/api_client.dart';
 import '../data/api/auth_api.dart';
 import '../data/api/chat_api.dart';
 import '../data/api/notes_api.dart';
+import '../data/api/quick_capture_api.dart';
 import '../data/api/tasks_api.dart';
 import '../data/repositories/auth_repository.dart';
 import '../data/repositories/chat_repository.dart';
@@ -40,6 +41,10 @@ final chatApiProvider = Provider<ChatApi>((ref) {
   return ChatApi(ref.watch(dioProvider));
 });
 
+final quickCaptureApiProvider = Provider<QuickCaptureApi>((ref) {
+  return QuickCaptureApi(ref.watch(dioProvider));
+});
+
 final authRepositoryProvider = Provider<AuthRepository>((ref) {
   return AuthRepository(ref.watch(authApiProvider));
 });