Version 3.1.5-beta2

Iterative beta on top of 3.1.5-beta1. One change: multi-zone HRUs (Itho DuoZone) now show up on the RF Status page instead of looking offline.

Fix — multi-zone 31DA / 31D9 acceptance (#366)

parseRF31DA and parseRF31D9 dropped every frame whose first payload byte wasn't 0x00. On Itho DuoZone HRUs (e.g. HRU ECO 300 R, model 03-00630) the unit broadcasts the same opcode once per zone, with the zone ID in that byte (0x15 / 0x16 / 0x17 for the typical living + sleeping + combined arrangement). All frames were therefore dropped and the source looked offline on /api/v2/rfstatus.

The guard is gone. The latest seen domain byte is now recorded on the rfStatusSource as lastZone31DA / lastZone31D9 and surfaced as zone31DA / zone31D9 in the /api/v2/rfstatus JSON output. Multi-zone consumers see the most recently broadcast zone's data rotating between zones; the new fields tell them which zone the current snapshot is from. Single-zone units stay at 0 and behave exactly as before.

Proper per-zone storage — separate measurements per zone surfaced simultaneously — is a follow-up. This release is the minimum unblock: from "no data" to "live data with a zone indicator".