An admin can now say "you edit Step 1 Cardiology" rather than only "you edit this
category". Each dimension on a grant is nullable and means "any"; a grant covers
the questions matching all the dimensions it sets, and holding several grants is
the union of their coverage (migration c1d2e3f4a5b6). A check constraint refuses
a grant that names nothing, which would otherwise mean "everything".
Permission checks now run against a predicate over Question rather than a set of
category ids, so the exam and discipline dimensions actually take effect on edit,
delete and bulk actions instead of being silently ignored.
Pediatrics is unbound back to a global tag. With counts already scoped by the
learner's active exam, one global row gives the right number per exam, so
scoping the row bought nothing and duplicating a 6,740-tag vocabulary per exam
would have to be repeated for every rename and merge.
Tests: 123 backend green.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01365DYKu14YtsBKv2ycW6eG
