Firmware:
- mDNS announcement as <hostname>.local (configurable via Kconfig)
- Task watchdog with 30s timeout and auto-reboot on hang
- STATUS now returns human-readable uptime (e.g., 3d2h15m) and hostname
Pi-side tools:
- esp-cmd: mDNS hostname resolution (esp-cmd amber-maple.local STATUS)
- esp-fleet: parallel command to all sensors (esp-fleet status)
Tested on amber-maple — mDNS resolves, watchdog active, fleet tool works.
