Add note for custom Node.js server implementation

[hyunbinseo]

Describe the problem

Alternatively, you can import the handler.js file, which exports a handler suitable for use with Express, …

https://svelte.dev/docs/kit/adapter-node#Custom-server

While these environment values are referenced by handler.js:

env('ADDRESS_HEADER', '').toLowerCase();
env('BODY_SIZE_LIMIT', '512K'));
env('HOST_HEADER', '').toLowerCase();
env('ORIGIN', undefined));
env('PORT_HEADER', '').toLowerCase();
env('PROTOCOL_HEADER', '').toLowerCase();
env('XFF_DEPTH', '1'));

these are only referenced by start.js, and must be manually implemented.

env('HEADERS_TIMEOUT');
env('HOST', '0.0.0.0');
env('IDLE_TIMEOUT', '0'));
env('KEEP_ALIVE_TIMEOUT');
env('LISTEN_FDS', '0'));
env('LISTEN_PID', '0'));
env('PORT', !path && '3000');
env('SHUTDOWN_TIMEOUT', '30'));
env('SOCKET_PATH', false);

The example code does give a hint, but it isn't explicit:

// PORT environment variable does not seem to be utilized by `my-server.js`

app.listen(3000, () => {
  console.log('listening on port 3000');
});

Describe the proposed solution

Add a table showing what environment variables and their features must be manually implemented.

A more in-depth example with a modern library would be also nice. (e.g. Hono)

Alternatives considered

No response

Importance

nice to have

Additional Information

No response