When a PATCH /appointments/:id extends endTime beyond the original, detect
and automatically shift downstream same-groomer appointments by the overrun
delta plus buffer. Only affects scheduled/confirmed appointments; appointments
that would shift outside business hours are flagged for manual review.
Clients receive email notification of rescheduled times.
GRO-1175: GRO-1162-G
Co-Authored-By: Paperclip <noreply@paperclip.ing>
