- add jz_bm_materials.revision (default 1), read-only for GORM
- bump it only on content changes (models.ReviseMaterial)
- PUT /materials/{id} locks the row and answers 409 to a stale revision
- management answers carry revision and updated_at, the student detail
carries revision
A material may be private: only its author and the users it is shared
with see it. Every student read (list, detail, course detail and
counters, the checklist linked material, the token twins) goes through
one visibility fragment. Existing materials stay public with no author.
GET/PUT /_bm/api/v1/materials/{id}/access let the author, a material
manager, toggle the flag and pick the users; the first change of an
author-less material makes the caller its author.
The material admin form gets the "Na zjazd" picker, every student
material JSON carries meeting_id, and GET /materials accepts meeting=
inside the published-only scope, so the Pulpit hero can list the
zjazd's materials next to its readings.
Datepickers on native time.Time / lagoon.Date fields, file uploads on
materials, readings and class sessions managed from the course form
(course_id made nullable).
Courses, meetings, class sessions, deadlines, readings with per-user
progress, materials with tags and file attachments. Timestamps are
stored in UTC and held as Europe/Warsaw text so the admin text inputs
can write them.
