Supervision now lives on the resource itself instead of being asked for again at
booking time, so one relation answers it everywhere.
The column is deliberately separate from the existing doctor_id bridge. That
bridge means "this resource IS this doctor" and isPerson() uses it to pin
capacity at 1; a supervised three-seat device must not become a person resource.
The FK is SET NULL rather than CASCADE because deleting a doctor should not take
the clinic's laser with it.
Required on create and non-clearable on update, enforced in the API where it can
give a Persian message. Ownership is checked through Clinic::hasDoctor so a
secretary cannot put their device under a doctor of another clinic; that returns
404, not 403, keeping foreign data invisible.
The 13 existing resources are backfilled deterministically: a practice resource
gets its own doctor, a clinic resource gets that clinic's first doctor. Both are
editable from the resource form.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
