Reduce dashboard CPU: cache DB, suppress logs, add systemd service

- Suppress Flask request logs (werkzeug ERROR only)
- Cache SQLite connection with WAL + 8MB cache
- Increase poll_ms 500->1000, history refresh 30s->60s
- Show 'waiting for pipeline...' when /dev/shm empty
- Add chicken-dashboard.service for systemd auto-start

chicken-dashboard.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=Chicken Counter Dashboard
+After=network.target
+
+[Service]
+Type=simple
+User=dsutanto
+WorkingDirectory=/media/jetson/DATA/.Codes/chicken-counting-sukawarna-det
+ExecStart=/usr/bin/python3 dashboard.py --port 8080 --db chicken_counts.db
+Restart=always
+RestartSec=5
+Environment=PYTHONUNBUFFERED=1
+
+[Install]
+WantedBy=multi-user.target