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/Validators/PatchCafeSettingsRequestValidator.cs

@@ -0,0 +1,28 @@
+using FluentValidation;
+using Meezi.API.Models.Cafes;
+
+namespace Meezi.API.Validators;
+
+public class PatchCafeSettingsRequestValidator : AbstractValidator<PatchCafeSettingsRequest>
+{
+    public PatchCafeSettingsRequestValidator()
+    {
+        RuleFor(x => x.Name).MaximumLength(200).When(x => x.Name is not null);
+        RuleFor(x => x.Phone).MaximumLength(20).When(x => x.Phone is not null);
+        RuleFor(x => x.Address).MaximumLength(500).When(x => x.Address is not null);
+        RuleFor(x => x.City).MaximumLength(100).When(x => x.City is not null);
+        RuleFor(x => x.Description).MaximumLength(2000).When(x => x.Description is not null);
+        RuleFor(x => x.LogoUrl).MaximumLength(500).When(x => x.LogoUrl is not null);
+        RuleFor(x => x.CoverImageUrl).MaximumLength(500).When(x => x.CoverImageUrl is not null);
+        RuleFor(x => x.SnappfoodVendorId).MaximumLength(100).When(x => x.SnappfoodVendorId is not null);
+        When(x => x.Theme is not null, () =>
+        {
+            RuleFor(x => x.Theme!.PaletteId).NotEmpty().MaximumLength(48);
+            RuleFor(x => x.Theme!.PanelStyle).NotEmpty().MaximumLength(24);
+            RuleFor(x => x.Theme!.MenuStyle).NotEmpty().MaximumLength(24);
+            RuleFor(x => x.Theme!.MenuTexture).NotEmpty().MaximumLength(24);
+            RuleFor(x => x.Theme!.Density).NotEmpty().MaximumLength(24);
+            RuleFor(x => x.Theme!.Radius).NotEmpty().MaximumLength(24);
+        });
+    }
+}