Initial commit: PriceGhost price tracking application

Full-stack application for tracking product prices:
- Backend: Node.js + Express + TypeScript
- Frontend: React + Vite + TypeScript
- Database: PostgreSQL
- Price scraping with Cheerio
- JWT authentication
- Background price checking with node-cron
- Price history charts with Recharts
- Docker support with docker-compose

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/context/AuthContext.tsx

@@ -0,0 +1,82 @@
+import {
+  createContext,
+  useContext,
+  useState,
+  useEffect,
+  ReactNode,
+} from 'react';
+import { authApi } from '../api/client';
+
+interface User {
+  id: number;
+  email: string;
+}
+
+interface AuthContextType {
+  user: User | null;
+  isLoading: boolean;
+  login: (email: string, password: string) => Promise<void>;
+  register: (email: string, password: string) => Promise<void>;
+  logout: () => void;
+}
+
+const AuthContext = createContext<AuthContextType | undefined>(undefined);
+
+export function AuthProvider({ children }: { children: ReactNode }) {
+  const [user, setUser] = useState<User | null>(null);
+  const [isLoading, setIsLoading] = useState(true);
+
+  useEffect(() => {
+    // Check for existing session on mount
+    const storedUser = localStorage.getItem('user');
+    const token = localStorage.getItem('token');
+
+    if (storedUser && token) {
+      try {
+        setUser(JSON.parse(storedUser));
+      } catch {
+        localStorage.removeItem('user');
+        localStorage.removeItem('token');
+      }
+    }
+    setIsLoading(false);
+  }, []);
+
+  const login = async (email: string, password: string) => {
+    const response = await authApi.login(email, password);
+    const { token, user: userData } = response.data;
+
+    localStorage.setItem('token', token);
+    localStorage.setItem('user', JSON.stringify(userData));
+    setUser(userData);
+  };
+
+  const register = async (email: string, password: string) => {
+    const response = await authApi.register(email, password);
+    const { token, user: userData } = response.data;
+
+    localStorage.setItem('token', token);
+    localStorage.setItem('user', JSON.stringify(userData));
+    setUser(userData);
+  };
+
+  const logout = () => {
+    localStorage.removeItem('token');
+    localStorage.removeItem('user');
+    setUser(null);
+  };
+
+  return (
+    <AuthContext.Provider value={{ user, isLoading, login, register, logout }}>
+      {children}
+    </AuthContext.Provider>
+  );
+}
+
+export function useAuth() {
+  const context = useContext(AuthContext);
+  if (context === undefined) {
+    throw new Error('useAuth must be used within an AuthProvider');
+  }
+  return context;
+}