userfront 런타임 BACKEND_URL fallback 수정

userfront/lib/core/services/runtime_env.dart

@@ -0,0 +1,34 @@
+import 'package:flutter_dotenv/flutter_dotenv.dart';
+
+String runtimeOriginFallback() {
+  try {
+    final origin = Uri.base.origin;
+    if (origin.isNotEmpty && origin != 'null') {
+      return origin;
+    }
+  } catch (_) {}
+  return 'https://sso-test.hmac.kr';
+}
+
+String envOrDefault(String key, String fallback) {
+  if (!dotenv.isInitialized) {
+    return fallback;
+  }
+  final value = dotenv.env[key];
+  if (value == null || value.trim().isEmpty) {
+    return fallback;
+  }
+  return value;
+}
+
+String sanitizedUrl(String value) {
+  return value.replaceAll(r'$', '').trim().replaceAll(RegExp(r'/$'), '');
+}
+
+String runtimeBackendUrl() {
+  return sanitizedUrl(envOrDefault('BACKEND_URL', runtimeOriginFallback()));
+}
+
+String runtimeUserfrontUrl() {
+  return sanitizedUrl(envOrDefault('USERFRONT_URL', runtimeOriginFallback()));
+}