v0.4.0's merge of public_booking_dict landed inside AvailabilityQuery and
left the two date fields orphaned after the helper's return, so
POST /api/v1/availability raised AttributeError on q.check_in (500) on
every install of that version. The RPC door reads the raw body and was
unaffected, which is why nothing noticed.
Put the helper next to public_room_dict and add a regression test that
constructs the query model and drives the endpoint through the
services layer.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
