Ports the state machine, retry/backoff, and guest-override detection from
the retired homeassistant-newbook-heating-component, without depending on
Home Assistant. Backend (Fastify/pg) + frontend (React/Vite/TS) following
standard stack conventions; LXC 128 (127 was already taken by utilities).
MHI/Midea/Daikin/boiler drivers and the shared MQTT broker (LXC 104) are
later phases/infra, not included here.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
