fix: sign out user immediately after signup to prevent Firestore access before verification

src/components/Login.tsx

@@ -44,6 +44,12 @@ export default function Login() {
         if (newUser) {
           try {
             await sendVerificationEmailToUser(newUser);
+            
+            // Sign them out immediately - they must verify before login
+            const { signOut } = await import('firebase/auth');
+            const { auth } = await import('@/lib/firebase');
+            await signOut(auth);
+            
             setVerificationSent(true);
             setShowVerificationBanner(true);
           } catch (err) {