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/google-sign-in-button.tsx

@@ -0,0 +1,21 @@
+'use client';
+
+import { signIn } from 'next-auth/react';
+
+export function GoogleSignInButton({ label }: { label: string }) {
+  return (
+    <button
+      type="button"
+      onClick={() => signIn('google', { callbackUrl: '/home' })}
+      className="w-full flex items-center justify-center gap-3 py-4 rounded-2xl border border-[var(--border)] bg-white dark:bg-white/5 text-sm font-medium hover:bg-slate-50 dark:hover:bg-white/10 transition-all"
+    >
+      <svg width="18" height="18" viewBox="0 0 48 48" aria-hidden>
+        <path fill="#FFC107" d="M43.611 20.083H42V20H24v8h11.303C33.654 32.657 29.203 36 24 36c-6.627 0-12-5.373-12-12s5.373-12 12-12c3.059 0 5.842 1.154 7.961 3.039l5.657-5.657C33.64 6.053 28.991 4 24 4 12.955 4 4 12.955 4 24s8.955 20 20 20 20-8.955 20-20c0-1.341-.138-2.65-.389-3.917z" />
+        <path fill="#FF3D00" d="m6.306 14.691 6.571 4.819C14.655 15.108 18.961 12 24 12c3.059 0 5.842 1.154 7.961 3.039l5.657-5.657C33.64 6.053 28.991 4 24 4 16.318 4 9.656 8.337 6.306 14.691z" />
+        <path fill="#4CAF50" d="M24 44c5.166 0 9.86-1.977 13.409-5.192l-6.19-5.238C29.211 35.091 26.715 36 24 36c-5.202 0-9.619-3.317-11.283-7.946l-6.522 5.025C9.505 39.556 16.227 44 24 44z" />
+        <path fill="#1976D2" d="M43.611 20.083H42V20H24v8h11.303a12.04 12.04 0 0 1-4.087 5.571l.003-.002 6.19 5.238C36.971 39.205 44 34 44 24c0-1.341-.138-2.65-.389-3.917z" />
+      </svg>
+      {label}
+    </button>
+  );
+}

memento-note/components/login-form.tsx

@@ -6,6 +6,19 @@ import { authenticate } from '@/app/actions/auth';
 import Link from 'next/link';
 import { Mail, Lock, ArrowRight, Sparkles } from 'lucide-react';
 import { useLanguage } from '@/lib/i18n';
+import { GoogleSignInButton } from '@/components/google-sign-in-button';
+
+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>
+  );
+}
 
 function LoginButton() {
   const { pending } = useFormStatus();
@@ -28,7 +41,13 @@ function LoginButton() {
   );
 }
 
-export function LoginForm({ allowRegister = true }: { allowRegister?: boolean }) {
+export function LoginForm({
+  allowRegister = true,
+  googleAuthEnabled = false,
+}: {
+  allowRegister?: boolean;
+  googleAuthEnabled?: boolean;
+}) {
   const [errorMessage, dispatch] = useActionState(authenticate, undefined);
   const { t } = useLanguage();
 
@@ -44,6 +63,13 @@ export function LoginForm({ allowRegister = true }: { allowRegister?: boolean })
           </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">

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">