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/Auth/AuthDtos.cs

@@ -0,0 +1,21 @@
+namespace Meezi.API.Models.Auth;
+
+public record SendOtpRequest(string Phone);
+
+public record VerifyOtpRequest(string Phone, string Code, string? CafeId = null);
+
+public record RefreshTokenRequest(string RefreshToken);
+
+public record AuthTokenResponse(
+    string AccessToken,
+    string RefreshToken,
+    DateTime ExpiresAt,
+    string UserId,
+    string CafeId,
+    string Role,
+    string PlanTier,
+    string Language,
+    string Actor = Meezi.Core.Constants.MeeziActorKinds.Merchant,
+    string? BranchId = null);
+
+public record SendOtpResponse(bool Sent, int ExpiresInSeconds);