AppointmentsPage now reads an optional ?date=YYYY-MM-DD query param as its
initial selected date. AppointmentEditPage and AppointmentCreatePage navigate
back to /admin/appointments?date=<the appointment's day> on save (and the edit
page's back link carries the date too), so the user returns to the day they
were viewing instead of today.
Test: AppointmentsPage honors ?date= and fetches that day.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>