Refactor context and provider structure for improved organization and maintainability

- Removed individual context files for Auth, Flyers, MasterItems, Modal, UserData, and their respective hooks.
- Introduced centralized provider files for each context, encapsulating logic and state management.
- Updated imports across the application to reflect the new structure, ensuring all hooks and contexts are correctly referenced.
- Enhanced the AppProviders component to streamline the wrapping of all context providers in the application.
- Improved type definitions and context management for better type safety and clarity.

src/hooks/useWatchedItems.test.tsx

@@ -2,15 +2,15 @@
 import { renderHook, act } from '@testing-library/react';
 import { describe, it, expect, vi, beforeEach } from 'vitest';
 import { useWatchedItems } from './useWatchedItems';
-import { useApi } from '../hooks/useApi';
-import { useAuth } from '../contexts/AuthContext';
-import { useUserData } from './useUserData';
+import { useApi } from './useApi';
+import { useAuth } from '../hooks/useAuth';
+import { useUserData } from '../hooks/useUserData';
 import type { MasterGroceryItem, User } from '../types';
 
 // Mock the hooks that useWatchedItems depends on
-vi.mock('../hooks/useApi');
-vi.mock('../contexts/AuthContext');
-vi.mock('./useUserData');
+vi.mock('./useApi');
+vi.mock('../hooks/useAuth');
+vi.mock('../hooks/useUserData');
 
 // The apiClient is globally mocked in our test setup, so we just need to cast it
 const mockedUseApi = vi.mocked(useApi);