feat: Enhance insurance billing system to support supplementary insurance

- Updated CoverageRule and related entities to include franchise_percent instead of franchise_rials.
- Modified Appointment entity to carry supplementary insurance ID alongside base insurance.
- Implemented SessionBillingService to ensure finalized invoices for insured patient sessions.
- Created InvoiceFinalized event to trigger claims creation upon invoice finalization.
- Added BackfillMissingClaimsCommand to generate claims for finalized invoices without existing claims.
- Developed tests to validate the new functionality for supplementary insurance handling in appointments and claims.

docs/architecture/insurance-billing-system.md

@@ -107,7 +107,7 @@ final readonly class CoverageRule
 | version | int | نسخه‌ی قرارداد (۱، ۲، …) |
 | is_active | bool | غیرفعال بدون حذف |
 | coverage_percent | decimal(5,2) | پوشش پیش‌فرض قرارداد |
-| franchise_rials | int | فرانشیز پیش‌فرض |
+| franchise_percent | decimal(5,2) | فرانشیز **درصدی** — سهم اجباری بیمار از مبلغ تحت پوشش؛ فقط در قرارداد تکمیلی اثر دارد |
 | annual_ceiling_rials | int null | سقف تعهد سالانه‌ی بیمار/بیمه |
 | effective_from | int (unix) | شروع اعتبار قرارداد |
 | effective_to | int null | پایان (null = جاری) |
@@ -125,7 +125,7 @@ override پوشش یک خدمت خاص تحت یک بیمه‌ی tenant (آیا
 | service_item_id | int FK→service_items |
 | covered | bool |
 | coverage_percent | decimal(5,2) null (null=ارث از قرارداد) |
-| franchise_rials | int null |
+| franchise_percent | decimal(5,2) null (null=ارث از قرارداد) |
 | ceiling_rials | int null |
 
 UniqueConstraint: `(tenant_insurance_id, service_item_id)`.
@@ -176,10 +176,6 @@ UniqueConstraint: `(service_item_id, year)`. `ServiceItem.priceRials` به‌ع
 | tariff_rials | int (تعرفه‌ی واحد) |
 | quantity | int |
 | total_rials | int (= tariff × qty) |
-| base_coverage_percent | decimal(5,2) |
-| supp_coverage_percent | decimal(5,2) |
-| franchise_rials | int |
-| ceiling_rials | int null |
 | base_insurance_rials | int |
 | supplementary_rials | int |
 | patient_rials | int |