feat(voice): dictate through the server's Claude Code login, no API key

The mic button previously needed a Deepgram API key, or fell back to the
browser's Web Speech engine. It can now transcribe through the same
speech-to-text service Claude Code's own /voice mode uses, so anyone signed
in to Claude Code on the server gets dictation with no third-party account.

Claude Code's voice mode cannot be driven directly: it opens the HOST's
microphone (sox/arecord), and the CLI runs in a headless tmux pane while the
human is in a browser somewhere else. So capture stays in the browser and only
the transcription backend is borrowed.

Audio goes browser -> Codeman -> Anthropic. The OAuth token never reaches the
page: the browser sends PCM16 (16 kHz mono, produced by an AudioWorklet since
MediaRecorder cannot emit raw PCM) and receives text.

- GET /api/voice/status reports readiness and never the token
- GET /ws/voice/stream relays one dictation, with the same Host/Origin upgrade
  guard as the terminal socket, plus caps on concurrency, stream length and
  frame size
- credentials are read-only: Codeman never refreshes them, since a refresh
  rotates the refresh token and could sign the user out of their own CLI
- claudeVoiceEnabled (synced, default OFF) gates the whole server side
- voiceSettings.provider picks auto/claude/deepgram/webspeech; auto prefers
  Claude, then a configured Deepgram key, then the browser

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/api-reference.md

@@ -471,6 +471,28 @@ All four enforce session ownership in multi-user mode; a foreign session id
 answers `404 NOT_FOUND` (no existence leak), and profiles of two owners of the
 same directory are distinct by construction.
 
+## Voice dictation
+
+Browser dictation transcribed through this server's Claude Code login, i.e. the
+same speech-to-text service the CLI's own `/voice` mode uses. Gated on the synced
+`claudeVoiceEnabled` setting (default OFF). Design:
+[`claude-voice-plan.md`](claude-voice-plan.md).
+
+- `GET /api/v1/voice/status` -> `{ available, reason?, subscriptionType?,
+  expiresAt? }`. `reason` is `disabled` (setting off), `no-credentials` (nobody
+  signed in to Claude Code on the server), `expired` (the access token elapsed;
+  running any Claude session refreshes it) or `malformed`. The OAuth token
+  itself is never returned by this or any other endpoint.
+- `GET /ws/voice/stream?language=&keyterms=` (WebSocket, not under `/api`)
+  relays one dictation. Client sends binary frames of signed 16-bit
+  little-endian PCM, 16 kHz mono (<= 64 KB per frame), plus JSON control frames
+  `{"t":"finalize"}` (ask for the final transcript) and `{"t":"stop"}`. Server
+  sends `{"t":"ready"}`, `{"t":"transcript","text","final"}` (each frame is the
+  WHOLE running transcript, not a delta), `{"t":"error","message"}` and
+  `{"t":"closed"}`. Close codes: `4003` disallowed Host/Origin, `4004`
+  unavailable (reason in the close reason), `4008` too many concurrent streams.
+  Streams are capped in count and length (`src/config/voice.ts`).
+
 ## Authentication
 
 Optional HTTP Basic (`CODEMAN_USERNAME`/`CODEMAN_PASSWORD`) → opaque