Large `__NEXT_PRIVATE_STANDALONE_CONFIG` causes `Error: spawn E2BIG`

### Link to the code that reproduces this issue https://github.com/hdodov/test-nextjs/tree/bug-env-too-large ### To Reproduce 1. Import a large JSON file in your `next.config.js` (e.g. to use as redirects) 2. Add some code that has to spawn a child process with the `child_process` module 3. Run Next with `output: "standalone"` and in prod mode 4. Run the app so that it runs the child process code 5. You'll see this error: ``` ⨯ Error: spawn E2BIG at d (.next/server/app/page.js:1:2287) at l (.next/server/app/page.js:1:2358) { errno: -7, code: 'E2BIG', syscall: 'spawn', digest: '1763947400' } ``` When logging `process.env`, you can see that basically **the entire JSON file is put in an environment variable**: <img width="1424" alt="Image" src="https://github.com/user-attachments/assets/fcf400f1-5583-4639-b288-e303932c3245" /> That's what causes the `E2BIG` error, which happens when a process is spawned with either too long arguments or a too large set of environment variables. ### Current vs. Expected behavior Currently, you get a warning in dev mode, if you have too many redirects: ``` $ pnpm dev > test-nextjs@0.1.0 dev /Users/hristiyan.dodov/Projects/test-nextjs > next dev ▲ Next.js 15.3.3 - Local: http://localhost:3000 - Network: http://192.168.1.129:3000 ✓ Starting... Warning: total number of custom routes exceeds 1000, this can reduce performance. Route counts: headers: 0 rewrites: 0 redirects: 2500 See more info: https://nextjs.org/docs/messages/max-custom-routes-reached ✓ Ready in 2.5s ``` What I'm expecting is to also see a warning that **an environment variable will hold ALL OF THEM as JSON**. For my case, the performance impact was negligible and it wasn't a problem. But the fact that we had **~0.5MB in environment variables** surely was. ### Provide environment information ```bash Operating System: Platform: darwin Arch: x64 Version: Darwin…