build: update start scripts in package.json

- Changed start:prod and start:stage scripts to use "next start" instead of the standalone server path.

Author: HMarzban

packages/webapp/package.json

@@ -6,8 +6,8 @@
     "dev": "next dev --turbopack",
     "build": "next build",
     "start": "next start",
-    "start:prod": "PORT=3001 node .next/standalone/packages/webapp/server.js",
-    "start:stage": "PORT=3000 node .next/standalone/packages/webapp/server.js",
+    "start:prod": "PORT=3001 node next start",
+    "start:stage": "PORT=3000 node next start",
     "pm2:start:stage": "pm2 reload pm2.config.js --env production --only nextjs_stage",
     "pm2:start:prod": "pm2 reload pm2.config.js --env production --only nextjs_production",
     "pm2:logs": "pm2 logs",