fix(e2ee): Add E2EE HKDF to voice.py, bot uses patched Dockerfile

voice.py runs in bot container, not agent container.
- Wait 3s for encryption key before connecting
- Build E2EE options with HKDF when key received
- Bot container now uses patched Dockerfile (needs FFI)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -11,7 +11,7 @@ services:
   bot:
     build:
       context: .
-      dockerfile: Dockerfile.bot
+      dockerfile: Dockerfile
     command: python bot.py
     env_file: .env
     restart: unless-stopped