feat(voice): on-demand PodMan voice test + Hermes notify + TTS tuning

Snapshot of in-progress voice work, committed to unblock concurrent edits: speakInRoom + POST voice-test endpoint, Test PodMan voice button (PodView/api), Hermes notify action + scripts/hermes-notify.mjs, agent exits on LiveKit disconnect for auto-restart, TTS playback tuning (subscriber-ready delay, preroll/tail silence, fallback line, microphone source), verify script updates.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/src/action/hermes.ts

@@ -1,6 +1,10 @@
 import type { Room } from '@livekit/rtc-node';
+import { Room as LiveKitRoom } from '@livekit/rtc-node';
+import { AccessToken } from 'livekit-server-sdk';
 import type { Collision, DataMessage, HermesMessage, Intervention } from '@podman/shared';
 import { DATA_TOPIC } from '@podman/shared';
+import { env } from '../env.js';
+import { speak } from '../voice/live.js';
 
 const encoder = new TextEncoder();
 
@@ -37,3 +41,52 @@ export async function publishHermesMessage(
     topic: DATA_TOPIC,
   });
 }
+
+export async function publishHermesIntervention(
+  room: Room,
+  collision: Collision,
+  intervention: Intervention,
+  voiceLine?: string,
+): Promise<void> {
+  const data: DataMessage = { type: 'COLLISION', collision, intervention };
+  await room.localParticipant?.publishData(encoder.encode(JSON.stringify(data)), {
+    reliable: true,
+    topic: DATA_TOPIC,
+  });
+  await publishHermesMessage(room, collision, intervention);
+  if (voiceLine) await speak(room, voiceLine);
+}
+
+async function hermesToken(roomName: string): Promise<string> {
+  const at = new AccessToken(env.LIVEKIT_API_KEY, env.LIVEKIT_API_SECRET, {
+    identity: `podman-hermes-${Date.now()}`,
+    name: 'PodMan Hermes',
+    ttl: '10m',
+  });
+  at.addGrant({
+    roomJoin: true,
+    room: roomName,
+    canPublish: true,
+    canSubscribe: true,
+    canPublishData: true,
+  });
+  return at.toJwt();
+}
+
+export async function notifyHermesInterventionInRoom(
+  roomName: string,
+  collision: Collision,
+  intervention: Intervention,
+  voiceLine?: string,
+): Promise<void> {
+  const room = new LiveKitRoom();
+  try {
+    await room.connect(env.LIVEKIT_URL, await hermesToken(roomName), {
+      autoSubscribe: false,
+      dynacast: false,
+    });
+    await publishHermesIntervention(room, collision, intervention, voiceLine);
+  } finally {
+    await room.disconnect().catch(() => {});
+  }
+}