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>

src/Meezi.Core/Interfaces/ITenantContext.cs

@@ -0,0 +1,17 @@
+using Meezi.Core.Enums;
+
+namespace Meezi.Core.Interfaces;
+
+public interface ITenantContext
+{
+    string? UserId { get; }
+    string? CafeId { get; }
+    EmployeeRole? Role { get; }
+    PlanTier? PlanTier { get; }
+    string? Language { get; }
+    /// <summary>Active branch from JWT when employee is branch-scoped.</summary>
+    string? BranchId { get; }
+    bool IsSystemAdmin { get; }
+    bool IsAuthenticated { get; }
+    bool IsCafeOwner => Role == EmployeeRole.Owner;
+}