Frontend api.ts baseUrl is already "/api", so paths like
"/api/cases" produced "/api/api/cases". Stripped the redundant
prefix from all component calls. Rewrite destination correctly
adds /api/ back for the Go backend.
- /termine page with list/calendar view toggle
- AppointmentList: date-grouped list with type/case filtering, summary cards
- AppointmentCalendar: month grid with colored type dots, clickable days/appointments
- AppointmentModal: create/edit/delete with case linking, type selection, location