The schedule showed a lecturer only where the session notes named one
(Globalizacja), so the student plan had nobody under the other courses.
The session JSON now carries the course lecturer in its course ref and an
optional per-session lecturer (new nullable column, admin field, seed key)
for courses shared between two people. The student app shows the
session's own lecturer or, failing that, the course's.
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.
