infra: use flock gateway lock

package.json

@@ -45,6 +45,7 @@
     "detect-libc": "^2.1.2",
     "dotenv": "^17.2.3",
     "express": "^5.2.1",
+    "fs-ext": "^2.1.1",
     "grammy": "^1.38.4",
     "json5": "^2.2.3",
     "qrcode-terminal": "^0.12.0",
@@ -59,6 +60,7 @@
     "@mariozechner/mini-lit": "0.2.1",
     "@types/body-parser": "^1.19.6",
     "@types/express": "^5.0.6",
+    "@types/fs-ext": "^2.0.3",
     "@types/node": "^24.10.2",
     "@types/qrcode-terminal": "^0.12.2",
     "@types/ws": "^8.18.1",