테넌트 접근 제한 안내화면 개선

userfront/lib/main.dart

@@ -1,4 +1,6 @@
 // ignore_for_file: avoid_print
+import 'dart:convert';
+
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
@@ -38,6 +40,19 @@ import 'i18n.dart';
 
 final _log = Logger('Main');
 
+Map<String, dynamic>? _decodeErrorDetails(String? raw) {
+  if (raw == null || raw.trim().isEmpty) {
+    return null;
+  }
+  try {
+    final decoded = jsonDecode(raw);
+    if (decoded is Map<String, dynamic>) {
+      return decoded;
+    }
+  } catch (_) {}
+  return null;
+}
+
 void _attemptRecoveryFromNullCheck({
   required Object exception,
   StackTrace? stackTrace,
@@ -398,6 +413,7 @@ final _router = GoRouter(
                     errorCode: params['error'],
                     description:
                         params['error_description'] ?? params['message'],
+                    tenantAccessDetails: _decodeErrorDetails(params['details']),
                   ),
                 );
               },