Initial commit: Camera Viewer with Frigate alerts

Features:
- 8-camera WebRTC grid using go2rtc
- MQTT subscription to Frigate events
- Auto-fullscreen on person detection (Front_Porch)
- SSE for real-time browser updates
- Touch-friendly tablet interface
- Wake lock to keep screen on
- Auto-dismiss after 30 seconds

camera-viewer.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=Camera Viewer - Live camera grid with Frigate alerts
+After=network.target
+
+[Service]
+Type=simple
+User=root
+WorkingDirectory=/opt/camera-viewer
+ExecStart=/opt/camera-viewer/venv/bin/uvicorn app.main:app --host 0.0.0.0 --port 8080
+Restart=always
+RestartSec=5
+Environment=PYTHONUNBUFFERED=1
+
+[Install]
+WantedBy=multi-user.target