fix: verify-only magic link approval flow

userfront/lib/core/services/auth_proxy_service.dart

@@ -125,7 +125,7 @@ class AuthProxyService {
     throw Exception('Polling failed: ${response.body}');
   }
 
-  static Future<Map<String, dynamic>> verifyMagicLink(String token) async {
+  static Future<Map<String, dynamic>> verifyMagicLink(String token, {bool verifyOnly = false}) async {
     final url = Uri.parse('$_baseUrl/api/v1/auth/magic-link/verify');
     
     final response = await http.post(
@@ -133,6 +133,7 @@ class AuthProxyService {
       headers: {'Content-Type': 'application/json'},
       body: jsonEncode({
         'token': token,
+        'verifyOnly': verifyOnly,
       }),
     );