feat(auth): implement email verification process with resend functionality and update registration flow

app/api/auth/verify-email/route.ts

@@ -0,0 +1,32 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { consumeVerificationToken } from '@/lib/email-verification';
+import { rateLimit } from '@/lib/rate-limit';
+import { logError } from '@/lib/logger';
+
+// A raw 32-byte hex token is exactly 64 characters.
+const TOKEN_REGEX = /^[0-9a-f]{64}$/;
+
+export async function GET(request: NextRequest) {
+    try {
+        // Rate-limit by IP to prevent token enumeration attacks.
+        const limited = await rateLimit(request, 'verify-email');
+        if (limited) return limited;
+
+        const token = request.nextUrl.searchParams.get('token');
+
+        if (!token || !TOKEN_REGEX.test(token.trim())) {
+            return NextResponse.redirect(new URL('/login?error=InvalidVerificationToken', request.url));
+        }
+
+        const email = await consumeVerificationToken(token.trim());
+
+        if (!email) {
+            return NextResponse.redirect(new URL('/login?error=InvalidVerificationToken', request.url));
+        }
+
+        return NextResponse.redirect(new URL('/login?verified=true', request.url));
+    } catch (err) {
+        logError('Email verification error:', err);
+        return NextResponse.redirect(new URL('/login?error=VerificationFailed', request.url));
+    }
+}