userfront 런타임 BACKEND_URL fallback 수정

userfront/lib/main.dart

@@ -3,6 +3,7 @@ import 'dart:async';
 import 'dart:convert';
 
 import 'package:flutter/foundation.dart';
+import 'package:flutter_dotenv/flutter_dotenv.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:easy_localization/easy_localization.dart' hide tr;
@@ -161,10 +162,20 @@ bool _shouldRunStartupSessionRecovery(Uri uri) {
   return !isPublicAuthPath(path, uri);
 }
 
+Future<void> _loadRuntimeEnv() async {
+  for (final fileName in const ['assets/.env', '.env']) {
+    try {
+      await dotenv.load(fileName: fileName);
+      return;
+    } catch (_) {}
+  }
+}
+
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
   usePathUrlStrategy();
   await EasyLocalization.ensureInitialized();
+  await _loadRuntimeEnv();
   LocaleRegistry.primeWithDefaults();
 
   // 1. Global Error Handling