Time the requests served on the internal listener

[HMarzban]

Problem

The internal listener records no request duration.

The REST app times every route: app.use('*', httpMetricsMiddleware()) (apps/hocuspocus.server/src/index.ts:38). The internal Hono app does not (apps/hocuspocus.server/src/hocuspocus.server.ts:596-601), and it is served by its own Bun.serve (apps/hocuspocus.server/src/hocuspocus.server.ts:608).

That listener carries content apply, checkpoint and restore, on the port set by HOCUSPOCUS_INTERNAL_HTTP_PORT: numericString('4003') (apps/hocuspocus.server/src/config/env.schema.ts:49). Those calls run in the WebSocket process, beside the live Y.Doc, so they are the ones most able to stall other people's typing.

When someone reports a slow content apply, an operator has no latency number to look at.

What to do

Mount the same middleware on the internal app, right after it is created:

internalApp.use('*', httpMetricsMiddleware())

Add httpMetricsMiddleware to the existing ./lib/metrics import at apps/hocuspocus.server/src/hocuspocus.server.ts:21-34.

Acceptance

• After one content apply, /metrics shows an http_request_duration_seconds sample for that route.
• /metrics itself still answers, because it is handled before the Hono dispatch.

Notes

The histogram already carries a route label (apps/hocuspocus.server/src/lib/metrics.ts:28-30), so the new samples separate apply from checkpoint and restore with no extra work.