[userfront] source 개념삭제. redirect 동작 정리

userfront/lib/features/auth/presentation/login_screen.dart

@@ -1149,8 +1149,13 @@ class _LoginScreenState extends ConsumerState<LoginScreen>
       }
     }
 
-    if (WebAuthIntegration.isPopup() ||
-        (_redirectUrl != null && _redirectUrl!.isNotEmpty)) {
+    final uri = Uri.base;
+    final redirectParam =
+        uri.queryParameters['redirect_uri'] ?? uri.queryParameters['redirect_url'];
+    final hasRedirectParam =
+        redirectParam != null && redirectParam.isNotEmpty;
+
+    if (WebAuthIntegration.isPopup() || hasRedirectParam) {
       debugPrint(
         "[Auth] External integration detected (popup or redirect). Notifying...",
       );