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/contexts/UserDataContext.ts

@@ -0,0 +1,14 @@
+// src/contexts/UserDataContext.ts
+import React from 'react';
+import type { MasterGroceryItem, ShoppingList } from '../types';
+
+export interface UserDataContextType {
+  watchedItems: MasterGroceryItem[];
+  shoppingLists: ShoppingList[];
+  setWatchedItems: React.Dispatch<React.SetStateAction<MasterGroceryItem[]>>;
+  setShoppingLists: React.Dispatch<React.SetStateAction<ShoppingList[]>>;
+  isLoading: boolean;
+  error: string | null;
+}
+
+export const UserDataContext = React.createContext<UserDataContextType | undefined>(undefined);