Import guest's preferred language from Guesty and use it for Autopilot / Scheduled Messages

Guesty already stores the guest's preferred language on each reservation (imported from Airbnb, Booking.com, and Vrbo). It would be great if ProhostAI pulled this field in and used it as the primary signal for choosing the right language when responding via Autopilot and when sending Scheduled Messages — rather than relying solely on the language the guest happens to write in.

It would also be really useful to have this language displayed directly on the reservation view, so hosts can quickly check which language a given guest speaks — for example, to prepare the right physical materials (welcome cards, instructions, etc.) left in the property ahead of their stay.