Expose staff-scoped kitchen voice playback status

[sridharkalaibala]

Expose kitchen playback status to authenticated Captain staff, scoped to their own messages and branch. Status contains speaker progress without recorded audio. This supports the general kitchen voice-note screen in Captain.

Validation: 24 kitchen audio tests pass, including sender isolation, retry deduplication, speaker recovery and sequential playback. Attribution check passes.

[github-actions]

Merged to develop. Anyone can test this - you do not need write access.

Try it at https://develop.posnic.io, or run it yourself:

git fetch origin develop && git checkout develop
npm install && npm --prefix api install
npm run dev   # then http://localhost:3000

When you have tested it, say what you did and what happened, and set
QA passed or QA failed. If you cannot set labels, just comment -
a maintainer will.

Reporting that something is broken is as useful as fixing it. It is
better found here than by a shopkeeper.