When an appointment is confirmed, the auto-created PatientSession was saved
empty: session_at null, visit_price_rials 0, no service line items, totals 0.
Now it copies the visit datetime from the appointment slot, the visit price
(falling back to the tenant free-visit price), a SessionService line per
appointment service (price snapshot from the service), and computes
services_total_rials / final_price_rials. Verified end-to-end.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
