chore: update Node version and enhance package scripts

- Updated Node version in .nvmrc from 24.0.0-nightly to 23.5.0 for better compatibility.
- Modified package.json to include a prestart script for Prisma generation and adjusted the start script to enable watch mode.
- Removed unused import from document.schema.ts to clean up the code.
- Added keepAlive setting for subscriptions in graphql.module.ts to improve connection stability.

These changes aim to streamline the development environment and enhance the application's performance and maintainability.

package.json

@@ -6,9 +6,9 @@
   "private": true,
   "license": "UNLICENSED",
   "scripts": {
+    "prestart": "npm run prisma:generate",
+    "start": "nest start --watch",
     "build": "nest build",
-    "start": "nest start",
-    "start:dev": "nest start --watch",
     "start:debug": "nest start --debug --watch",
     "start:prod": "node dist/main",
     "prisma:generate": "npx prisma generate --schema=./epess-database/prisma/schema.prisma",