Fastify rejects POST requests that carry Content-Type: application/json
but an empty body (JSON.parse('') throws). Both no-body POSTs now send {}.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Unsellable flag is in-app visibility only; staff mark rooms out of
order in NewBook through their own process. NewBook use is now
read-only (room sync + occupancy filter).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>