Expose session services + per-session billing summary (invoice_uuid, invoice_status, patient_debt_rials, is_paid) on the sessions endpoint. Add 'سرویسها' card tab in my-patients: cost, remaining debt, complete payment (PATCH session), and invoice view modal. Grant secretary access in BillingController.resolveEntity. Update patient.md + billing.md. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>