feat(tui): match CLI's voice slash + VAD-continuous recording model

The TUI had drifted from the CLI's voice model in two ways:

- /voice on was lighting up the microphone immediately and Ctrl+B was
  interpreted as a mode toggle.  The CLI separates the two: /voice on
  just flips the umbrella bit, recording only starts once the user
  presses Ctrl+B, which also sets _voice_continuous so the VAD loop
  auto-restarts until the user presses Ctrl+B again or three silent
  cycles pass.
- /voice tts was missing entirely, so users couldn't turn agent reply
  speech on/off from inside the TUI.

This commit brings the TUI to parity.

Python

- hermes_cli/voice.py: continuous-mode API (start_continuous,
  stop_continuous, is_continuous_active) layered on the existing PTT
  wrappers. The silence callback transcribes, fires on_transcript,
  tracks consecutive no-speech cycles, and auto-restarts — mirroring
  cli.py:_voice_stop_and_transcribe + _restart_recording.
- tui_gateway/server.py:
  - voice.toggle now supports on / off / tts / status.  The umbrella
    bit lives in HERMES_VOICE + display.voice_enabled; tts lives in
    HERMES_VOICE_TTS + display.voice_tts.  /voice off also tears down
    any active continuous loop so a toggle-off really releases the
    microphone.
  - voice.record start/stop now drives start_continuous/stop_continuous.
    start is refused with a clear error when the mode is off, matching
    cli.py:handle_voice_record's early return on `not _voice_mode`.
  - New voice.transcript / voice.status events emit through
    _voice_emit (remembers the sid that last enabled the mode so
    events land in the right session).

TypeScript

- gatewayTypes.ts: voice.status + voice.transcript event
  discriminants; VoiceToggleResponse gains tts; VoiceRecordResponse
  gains status for the new "started/stopped" responses.
- interfaces.ts: GatewayEventHandlerContext gains composer.setInput +
  submission.submitRef + voice.{setRecording, setProcessing,
  setVoiceEnabled}; InputHandlerContext.voice gains enabled +
  setVoiceEnabled for the mode-aware Ctrl+B handler.
- createGatewayEventHandler.ts: voice.status drives REC/STT badges;
  voice.transcript auto-submits when the composer is empty (CLI
  _pending_input.put parity) and appends when a draft is in flight.
  no_speech_limit flips voice off + sys line.
- useInputHandlers.ts: Ctrl+B now calls voice.record (start/stop),
  not voice.toggle, and nudges the user with a sys line when the
  mode is off instead of silently flipping it on.
- useMainApp.ts: wires the new event-handler context fields.
- slash/commands/session.ts: /voice handles on / off / tts / status
  with CLI-matching output ("voice: mode on · tts off").

Backward compat preserved for voice.record (was always PTT shape;
gateway still honours start/stop with mode-gating added).

ui-tui/src/app/createGatewayEventHandler.ts

@@ -51,6 +51,9 @@ export function createGatewayEventHandler(ctx: GatewayEventHandlerContext): (ev:
   const { STARTUP_RESUME_ID, newSession, resumeById, setCatalog } = ctx.session
   const { bellOnComplete, stdout, sys } = ctx.system
   const { appendMessage, panel, setHistoryItems } = ctx.transcript
+  const { setInput } = ctx.composer
+  const { submitRef } = ctx.submission
+  const { setProcessing: setVoiceProcessing, setRecording: setVoiceRecording, setVoiceEnabled } = ctx.voice
 
   let pendingThinkingStatus = ''
   let thinkingStatusTimer: null | ReturnType<typeof setTimeout> = null
@@ -261,6 +264,60 @@ export function createGatewayEventHandler(ctx: GatewayEventHandlerContext): (ev:
         return
       }
 
+      case 'voice.status': {
+        // Continuous VAD loop reports its internal state so the status bar
+        // can show listening / transcribing / idle without polling.
+        const state = String(ev.payload?.state ?? '')
+
+        if (state === 'listening') {
+          setVoiceRecording(true)
+          setVoiceProcessing(false)
+        } else if (state === 'transcribing') {
+          setVoiceRecording(false)
+          setVoiceProcessing(true)
+        } else {
+          setVoiceRecording(false)
+          setVoiceProcessing(false)
+        }
+
+        return
+      }
+
+      case 'voice.transcript': {
+        // CLI parity: the 3-strikes silence detector flipped off automatically.
+        // Mirror that on the UI side and tell the user why the mode is off.
+        if (ev.payload?.no_speech_limit) {
+          setVoiceEnabled(false)
+          setVoiceRecording(false)
+          setVoiceProcessing(false)
+          sys('voice: no speech detected 3 times, continuous mode stopped')
+
+          return
+        }
+
+        const text = String(ev.payload?.text ?? '').trim()
+
+        if (!text) {
+          return
+        }
+
+        // Match CLI's _pending_input.put(transcript): auto-submit when the
+        // composer is empty, otherwise append so the user can keep editing
+        // a partial draft they were working on.
+        setInput(prev => {
+          if (!prev) {
+            // defer submit so React commits the state change first
+            setTimeout(() => submitRef.current(text), 0)
+
+            return ''
+          }
+
+          return `${prev}${/\s$/.test(prev) ? '' : ' '}${text}`
+        })
+
+        return
+      }
+
       case 'gateway.start_timeout': {
         const { cwd, python } = ev.payload ?? {}
         const trace = python || cwd ? ` · ${String(python || '')} ${String(cwd || '')}`.trim() : ''