The management API could only upsert a material on its title and course,
so a renamed note became a second material. PUT /materials/{id} applies the
same body to one material (422 when the new title and course belong to
another one), GET /materials/{id} shows a draft or published material with
its public files, and the upsert, update and validation share one path.
The README documents the management API.
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).
Validates a whole JSON file (course keys, meeting numbers, values, dates)
and upserts meetings, courses, class sessions, deadlines and readings in
one transaction, matched on their natural identity. Prints a created,
updated and unchanged summary; --dry-run only validates. Ships a small
example fixture with made-up data.
