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>

src/web/routes/index.ts

@@ -24,4 +24,5 @@ export { registerSearchRoutes } from './search-routes.js';
 export { registerMeRoutes } from './me-routes.js';
 export { registerAdminRoutes } from './admin-routes.js';
 export { registerWsRoutes } from './ws-routes.js';
+export { registerVoiceRoutes } from './voice-routes.js';
 export { registerWebviewRoutes, tryWebviewRefererFallback } from './webview-routes.js';