fix(voice): keep LiveKit TTS tracks alive

infra/systemd/podman-gemini-starter-agent.service

@@ -0,0 +1,17 @@
+[Unit]
+Description=PodMan LiveKit Gemini starter agent
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+WorkingDirectory=/root/podman/examples/livekit-gemini-hacker-starter/agent
+Environment=PATH=/root/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+ExecStart=/root/.local/bin/uv run agent.py dev
+Restart=always
+RestartSec=3
+KillSignal=SIGTERM
+TimeoutStopSec=20
+
+[Install]
+WantedBy=multi-user.target