feat(auth): restore Google sign-in and AI admin test routes

Google OAuth was implemented locally but never deployed; the login button
only renders when AUTH_GOOGLE_ID and AUTH_GOOGLE_SECRET are set. Also
restores /api/ai/test-* endpoints removed by mistake and wires Google
credentials into deploy workflows.

Co-authored-by: Cursor <cursoragent@cursor.com>

memento-note/components/register-form.tsx

@@ -6,6 +6,7 @@ import { register } from '@/app/actions/register';
 import Link from 'next/link';
 import { Mail, Lock, User, ArrowRight, Sparkles } from 'lucide-react';
 import { useLanguage } from '@/lib/i18n';
+import { GoogleSignInButton } from '@/components/google-sign-in-button';
 
 function RegisterButton() {
   const { pending } = useFormStatus();
@@ -28,7 +29,19 @@ function RegisterButton() {
   );
 }
 
-export function RegisterForm() {
+function AuthDivider({ label }: { label: string }) {
+  return (
+    <div className="relative flex items-center py-2">
+      <div className="flex-grow border-t border-[var(--border)]" />
+      <span className="mx-4 text-[10px] uppercase tracking-widest text-[var(--muted-foreground)] font-bold">
+        {label}
+      </span>
+      <div className="flex-grow border-t border-[var(--border)]" />
+    </div>
+  );
+}
+
+export function RegisterForm({ googleAuthEnabled = false }: { googleAuthEnabled?: boolean }) {
   const [errorMessage, dispatch] = useActionState(register, undefined);
   const { t } = useLanguage();
 
@@ -44,6 +57,13 @@ export function RegisterForm() {
           </p>
         </div>
 
+        {googleAuthEnabled && (
+          <>
+            <GoogleSignInButton label={t('auth.continueWithGoogle')} />
+            <AuthDivider label={t('auth.orContinueWith')} />
+          </>
+        )}
+
         <form action={dispatch} className="space-y-4">
           <div className="space-y-1.5">
             <label className="text-[10px] uppercase tracking-widest font-bold text-[var(--muted-foreground)] px-4">