Initial implementation of Website Change Detection Monitor MVP

Features implemented:
- Backend API with Express + TypeScript
- User authentication (register/login with JWT)
- Monitor CRUD operations with plan-based limits
- Automated change detection engine
- Email alert system
- Frontend with Next.js + TypeScript
- Dashboard with monitor management
- Login/register pages
- Monitor history viewer
- PostgreSQL database schema
- Docker setup for local development

Technical stack:
- Backend: Express, TypeScript, PostgreSQL, Redis (ready)
- Frontend: Next.js 14, React Query, Tailwind CSS
- Database: PostgreSQL with migrations
- Services: Page fetching, diff detection, email alerts

Documentation:
- README with full setup instructions
- SETUP guide for quick start
- PROJECT_STATUS with current capabilities
- Complete technical specifications

Ready for local testing and feature expansion.

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

frontend/lib/api.ts

@@ -0,0 +1,90 @@
+import axios from 'axios';
+
+const API_URL = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:3001';
+
+export const api = axios.create({
+  baseURL: `${API_URL}/api`,
+  headers: {
+    'Content-Type': 'application/json',
+  },
+});
+
+// Add auth token to requests
+api.interceptors.request.use((config) => {
+  const token = localStorage.getItem('token');
+  if (token) {
+    config.headers.Authorization = `Bearer ${token}`;
+  }
+  return config;
+});
+
+// Handle auth errors
+api.interceptors.response.use(
+  (response) => response,
+  (error) => {
+    if (error.response?.status === 401) {
+      localStorage.removeItem('token');
+      localStorage.removeItem('user');
+      window.location.href = '/login';
+    }
+    return Promise.reject(error);
+  }
+);
+
+// Auth API
+export const authAPI = {
+  register: async (email: string, password: string) => {
+    const response = await api.post('/auth/register', { email, password });
+    return response.data;
+  },
+
+  login: async (email: string, password: string) => {
+    const response = await api.post('/auth/login', { email, password });
+    return response.data;
+  },
+};
+
+// Monitor API
+export const monitorAPI = {
+  list: async () => {
+    const response = await api.get('/monitors');
+    return response.data;
+  },
+
+  get: async (id: string) => {
+    const response = await api.get(`/monitors/${id}`);
+    return response.data;
+  },
+
+  create: async (data: any) => {
+    const response = await api.post('/monitors', data);
+    return response.data;
+  },
+
+  update: async (id: string, data: any) => {
+    const response = await api.put(`/monitors/${id}`, data);
+    return response.data;
+  },
+
+  delete: async (id: string) => {
+    const response = await api.delete(`/monitors/${id}`);
+    return response.data;
+  },
+
+  check: async (id: string) => {
+    const response = await api.post(`/monitors/${id}/check`);
+    return response.data;
+  },
+
+  history: async (id: string, limit = 50) => {
+    const response = await api.get(`/monitors/${id}/history`, {
+      params: { limit },
+    });
+    return response.data;
+  },
+
+  snapshot: async (id: string, snapshotId: string) => {
+    const response = await api.get(`/monitors/${id}/history/${snapshotId}`);
+    return response.data;
+  },
+};

frontend/lib/auth.ts

@@ -0,0 +1,29 @@
+export function saveAuth(token: string, user: any) {
+  localStorage.setItem('token', token);
+  localStorage.setItem('user', JSON.stringify(user));
+}
+
+export function getAuth() {
+  if (typeof window === 'undefined') return null;
+
+  const token = localStorage.getItem('token');
+  const userStr = localStorage.getItem('user');
+
+  if (!token || !userStr) return null;
+
+  try {
+    const user = JSON.parse(userStr);
+    return { token, user };
+  } catch {
+    return null;
+  }
+}
+
+export function clearAuth() {
+  localStorage.removeItem('token');
+  localStorage.removeItem('user');
+}
+
+export function isAuthenticated() {
+  return !!getAuth();
+}