Course workshops now show where they are edited

Workshop dates reused in a course now appear as clearly shared schedule details
instead of disabled form fields. Use **Edit shared workshop schedule** to open
the exact Workshop Library occurrence and safely change its date, time, room,
teacher, or public visibility.

The course access section now separates workshops already included in the
program from optional bookings outside the program. Included workshops are
listed visibly and marked as already available to active participants, so they
no longer appear to be missing from an empty optional-workshop picker.

Participant overrides now explain that a custom number is the total allowance
on the participant's existing course access pass. It does not issue another
pass or add that number on top of classes they already received with the
course.