Booking Sessions API

Two calendar-recovery endpoints over booking sessions (retrying a failed Google Calendar invite and claiming/repairing the session's calendar linkage). Board data, outcome stamps, and rescheduling live on the Bookings API, not here.

Code: src/api/routes/booking-sessions/index.ts. Full endpoint semantics, status-code maps, and the claim RPC are documented in Booking Sessions API & Confirm Path.