Refactor tests and API context integration

- Updated tests in `useShoppingLists`, `useWatchedItems`, and various components to use `waitFor` for asynchronous assertions.
- Enhanced error handling in `errorHandler` middleware tests to include validation errors and status codes.
- Modified `AuthView`, `ProfileManager.Auth`, and `ProfileManager.Authenticated` tests to check for `AbortSignal` in API calls.
- Removed duplicate assertions in `auth.routes.test`, `budget.routes.test`, and `gamification.routes.test`.
- Introduced reusable logger matcher in `budget.routes.test`, `deals.routes.test`, `flyer.routes.test`, and `user.routes.test`.
- Simplified API client mock in `aiApiClient.test` to handle token overrides correctly.
- Removed unused `apiUtils.ts` file.
- Added `ApiContext` and `ApiProvider` for better API client management in React components.

src/hooks/useWatchedItems.test.tsx

@@ -1,5 +1,5 @@
 // src/hooks/useWatchedItems.test.tsx
-import { renderHook, act } from '@testing-library/react';
+import { renderHook, act, waitFor } from '@testing-library/react';
 import { describe, it, expect, vi, beforeEach } from 'vitest';
 import { useWatchedItems } from './useWatchedItems';
 import { useApi } from './useApi';
@@ -122,7 +122,9 @@ describe('useWatchedItems Hook', () => {
         await result.current.removeWatchedItem(itemIdToRemove);
       });
 
-      expect(mockRemoveWatchedItemApi).toHaveBeenCalledWith(itemIdToRemove);
+      await waitFor(() => {
+        expect(mockRemoveWatchedItemApi).toHaveBeenCalledWith(itemIdToRemove);
+      });
       expect(mockSetWatchedItems).toHaveBeenCalledWith(expect.any(Function));
 
       // Verify the logic inside the updater function