Add UK/European thermostat support (Nest discontinued in UK)

With Google discontinuing the Nest Learning Thermostat and Nest Thermostat E in the UK/EU, UK hosts effectively have no currently-sold retail thermostat that works with Hospitable's heating automation. Current state of UK thermostat support: Nest — discontinued in UK, only available pre-owned via unverified sellers Honeywell — our supported models (T5, T6 Pro, T9, T10 Pro, etc.) are US Resideo-app devices; the UK retail equivalents (e.g. Honeywell Home T6R-HW) are not supported Ecobee / Sensi — not sold in UK Production data: of ~14,805 GB properties, only 11 thermostats are linked (8 Nest, 3 Honeywell Resideo) — and new UK hosts can no longer replicate even that. What UK hosts are asking for: A currently-sold, retail-available thermostat they can confidently buy for their portfolios Heating-only is acceptable — they understand hot water control isn't in scope Clarity on whether UK-market thermostat support is on the roadmap