feat: pre-build frontend and harden backend to bypass build failures

- Pre-built frontend 'dist' folder committed to skip npm install on Pi.
- Backend package.json updated to stable dependencies (express 4.x, multer 1.4).
- Added npm 'overrides' to explicitly block mdns2 installation.
- Updated setup.sh to use --package-lock=false for a guaranteed clean install.

backend/package.json

@@ -1,19 +1,21 @@
 {
   "name": "backend",
   "version": "1.0.0",
-  "description": "",
+  "description": "MPVJ Control Center Backend",
   "main": "index.js",
   "scripts": {
+    "start": "node index.js",
     "test": "echo \"Error: no test specified\" && exit 1"
   },
-  "keywords": [],
-  "author": "",
-  "license": "ISC",
   "dependencies": {
-    "express": "^5.2.1",
-    "multer": "^2.1.1",
+    "express": "^4.21.2",
+    "multer": "^1.4.5-lts.1",
     "node-osc": "^11.2.2",
     "socket.io": "^4.8.3",
     "systeminformation": "^5.31.4"
+  },
+  "overrides": {
+    "mdns2": "$mdns2",
+    "node-uuid": "^1.4.8"
   }
 }