add prettier to backend

backend/package.json

@@ -4,7 +4,9 @@
   "description": "",
   "main": "index.js",
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "lint": "eslint . --ext .js,.jsx,.cjs,.mjs,.ts,.tsx,.cts,.mts --fix --ignore-path .gitignore",
+    "format": "prettier --write src/"
   },
   "keywords": [],
   "author": "",
@@ -14,6 +16,7 @@
     "@typescript-eslint/eslint-plugin": "^7.1.1",
     "@typescript-eslint/parser": "^7.1.1",
     "eslint": "^8.57.0",
+    "prettier": "^3.2.5",
     "typescript": "^5.3.3"
   },
   "dependencies": {