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.API/Models/Crm/CouponDtos.cs

@@ -0,0 +1,50 @@
+using Meezi.Core.Enums;
+
+namespace Meezi.API.Models.Crm;
+
+public record CouponDto(
+    string Id,
+    string Code,
+    CouponType Type,
+    decimal Value,
+    decimal? MinOrderAmount,
+    decimal? MaxDiscount,
+    int? UsageLimit,
+    int UsedCount,
+    CustomerGroup? TargetGroup,
+    DateTime? StartsAt,
+    DateTime? ExpiresAt,
+    bool IsActive);
+
+public record CreateCouponRequest(
+    string Code,
+    CouponType Type,
+    decimal Value,
+    decimal? MinOrderAmount,
+    decimal? MaxDiscount,
+    int? UsageLimit,
+    CustomerGroup? TargetGroup,
+    DateTime? StartsAt,
+    DateTime? ExpiresAt,
+    bool IsActive = true);
+
+public record ValidateCouponRequest(string Code, decimal Subtotal);
+
+public record ValidateCouponResult(
+    string CouponId,
+    string Code,
+    CouponType Type,
+    decimal Value,
+    decimal DiscountAmount);
+
+public record UpdateCouponRequest(
+    string? Code,
+    CouponType? Type,
+    decimal? Value,
+    decimal? MinOrderAmount,
+    decimal? MaxDiscount,
+    int? UsageLimit,
+    CustomerGroup? TargetGroup,
+    DateTime? StartsAt,
+    DateTime? ExpiresAt,
+    bool? IsActive);