/services/public-calendar/{professionalId} exists after all — the web has been
using it all along. My earlier probes missed it because they guessed the URL
shape, and because it is keyed by the professionals row id rather than the
owning user id, which ProfessionalEntity was discarding.
Adds ProfessionalEntity.recordId and points the client calendar at the public
endpoint. Until now a client browsing a professional's availability was served
their own agenda, so every slot looked free and two people could book the same
hour. A failed load now hides the slots and offers a retry instead of showing
them as available.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
