feat(api): .NET 10 multi-tenant REST API

Full backend implementation:
- Multi-tenant cafe/restaurant management (menus, orders, tables, staff)
- POS order flow with ZarinPal and Snappfood payment integration
- OTP authentication via Kavenegar SMS
- QR digital menu with public discover/finder endpoints
- Customer loyalty, coupons, CRM
- PostgreSQL via EF Core, Redis for caching/sessions
- Background jobs, webhook handlers
- Full migration history

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

tests/Meezi.API.Tests/Integration/MeeziIntegrationCollection.cs

@@ -0,0 +1,6 @@
+using Xunit;
+
+namespace Meezi.API.Tests.Integration;
+
+[CollectionDefinition(nameof(MeeziIntegrationCollection))]
+public class MeeziIntegrationCollection : ICollectionFixture<MeeziWebApplicationFactory>;