chore: backend setup

server/package.json

@@ -9,5 +9,10 @@
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
-  "devDependencies": {}
+  "dependencies": {
+    "cors": "^2.8.6",
+    "dotenv": "^17.3.1",
+    "express": "^5.2.1",
+    "pg": "^8.19.0"
+  }
 }