🏗️ ci: Add build script for backend

Adds the `tsc` command to the `scripts` in `package.json`.
This enables Vercel to compile the TypeScript source code into JavaScript during the deployment process.

Author: 0disoft

backend/package.json

@@ -4,7 +4,8 @@
   "description": "",
   "main": "index.js",
   "scripts": {
-    "dev": "tsx watch src/index.ts"
+    "dev": "tsx watch src/index.ts",
+    "build": "tsc"
   },
   "type": "module",
   "keywords": [],