모바일 fallback 변경. .env유출 가능성 차단

userfront/scripts/dev-server.sh

@@ -10,8 +10,10 @@ set -- flutter run \
   --web-hostname 0.0.0.0 \
   --web-port "${USERFRONT_INTERNAL_PORT:-5000}" \
   --wasm \
+  --dart-define=BACKEND_URL="${BACKEND_URL:-}" \
   --dart-define=CLIENT_LOG_DEBUG="${CLIENT_LOG_DEBUG:-false}" \
   --dart-define=APP_ENV="${APP_ENV:-dev}" \
+  --dart-define=USERFRONT_URL="${USERFRONT_URL:-}" \
   ${USERFRONT_FLUTTER_RUN_FLAGS:-} \
   --no-web-resources-cdn