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/app/register/page.tsx

@@ -0,0 +1,129 @@
+'use client'
+
+import { useState } from 'react'
+import { useRouter } from 'next/navigation'
+import Link from 'next/link'
+import { authAPI } from '@/lib/api'
+import { saveAuth } from '@/lib/auth'
+
+export default function RegisterPage() {
+  const router = useRouter()
+  const [email, setEmail] = useState('')
+  const [password, setPassword] = useState('')
+  const [confirmPassword, setConfirmPassword] = useState('')
+  const [error, setError] = useState('')
+  const [loading, setLoading] = useState(false)
+
+  const handleSubmit = async (e: React.FormEvent) => {
+    e.preventDefault()
+    setError('')
+
+    if (password !== confirmPassword) {
+      setError('Passwords do not match')
+      return
+    }
+
+    if (password.length < 8) {
+      setError('Password must be at least 8 characters')
+      return
+    }
+
+    setLoading(true)
+
+    try {
+      const data = await authAPI.register(email, password)
+      saveAuth(data.token, data.user)
+      router.push('/dashboard')
+    } catch (err: any) {
+      const message = err.response?.data?.message || 'Failed to register'
+      const details = err.response?.data?.details
+
+      if (details && Array.isArray(details)) {
+        setError(details.join(', '))
+      } else {
+        setError(message)
+      }
+    } finally {
+      setLoading(false)
+    }
+  }
+
+  return (
+    <div className="flex min-h-screen items-center justify-center bg-gray-50 px-4">
+      <div className="w-full max-w-md">
+        <div className="rounded-lg bg-white p-8 shadow-lg">
+          <h1 className="mb-6 text-center text-3xl font-bold">Website Monitor</h1>
+          <h2 className="mb-6 text-center text-xl text-gray-600">Create Account</h2>
+
+          {error && (
+            <div className="mb-4 rounded-md bg-red-50 p-4 text-red-800">
+              {error}
+            </div>
+          )}
+
+          <form onSubmit={handleSubmit} className="space-y-4">
+            <div>
+              <label htmlFor="email" className="block text-sm font-medium text-gray-700">
+                Email
+              </label>
+              <input
+                id="email"
+                type="email"
+                value={email}
+                onChange={(e) => setEmail(e.target.value)}
+                required
+                className="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-primary focus:outline-none focus:ring-1 focus:ring-primary"
+              />
+            </div>
+
+            <div>
+              <label htmlFor="password" className="block text-sm font-medium text-gray-700">
+                Password
+              </label>
+              <input
+                id="password"
+                type="password"
+                value={password}
+                onChange={(e) => setPassword(e.target.value)}
+                required
+                className="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-primary focus:outline-none focus:ring-1 focus:ring-primary"
+              />
+              <p className="mt-1 text-xs text-gray-500">
+                At least 8 characters with uppercase, lowercase, and number
+              </p>
+            </div>
+
+            <div>
+              <label htmlFor="confirmPassword" className="block text-sm font-medium text-gray-700">
+                Confirm Password
+              </label>
+              <input
+                id="confirmPassword"
+                type="password"
+                value={confirmPassword}
+                onChange={(e) => setConfirmPassword(e.target.value)}
+                required
+                className="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-primary focus:outline-none focus:ring-1 focus:ring-primary"
+              />
+            </div>
+
+            <button
+              type="submit"
+              disabled={loading}
+              className="w-full rounded-md bg-primary px-4 py-2 font-medium text-white hover:bg-primary/90 disabled:opacity-50"
+            >
+              {loading ? 'Creating account...' : 'Create Account'}
+            </button>
+          </form>
+
+          <p className="mt-6 text-center text-sm text-gray-600">
+            Already have an account?{' '}
+            <Link href="/login" className="font-medium text-primary hover:underline">
+              Sign in
+            </Link>
+          </p>
+        </div>
+      </div>
+    </div>
+  )
+}