feat: PSv2 - Have visibility into which workers are subscribed to a job

[carlosgjs]

Summary

Can we show which consumers/workers are subscribed to a stream in the job logs? Or status screen? And/or the processing service registration list? NATS seems to make this easy to retrieve which is awesome.

[mihow]

Claude says: Per-job logs already show which worker requests and returns each task batch (#1238, merged). A full per-worker subscriber roster (hostname-level identity) is covered by the in-flight API-key identity work, PR #1194 / #1201. Linking for tracking.