Refactor code structure for improved readability and maintainability

runner/Dockerfile

@@ -1,4 +1,4 @@
-FROM node:20-alpine
+FROM node:22-alpine
 WORKDIR /app
 COPY package*.json ./
 RUN npm install

runner/package.json

@@ -1,13 +1,14 @@
-{
+{
   "name": "seltd-runner",
   "version": "1.0.0",
   "private": true,
   "type": "module",
   "scripts": {
-    "start": "node src/index.js"
+    "start": "node src/index.js",
+    "check": "node --check src/index.js"
   },
   "dependencies": {
     "ioredis": "^5.6.1",
     "mysql2": "^3.12.0"
   }
-}
+}