Add DELETE /api/admin/bookings/reserve to release admin walk-in/call-in reservations.
New handler AdminCancelReservationHandler targets only RESERVATION:admin:%
entries (partitioned from user RESERVATION:user:% by WHERE clause). Includes
12 tests covering walkin + callin success, isolation, no-op, unauth, empty ctx,
walkin+callin coexistence, anon untouched, response format parity, overlapping
reservations deleted, user reservations untouched, and idempotent double-cancel.
Inverse-isolation tests in cancel_reservation_test.go prove the user-side
DELETE /api/bookings/reserve does not touch admin or anon reservations.
popertots
c2aa0b93cb