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/HealthIntegrationTests.cs

@@ -0,0 +1,20 @@
+using System.Net;
+using Xunit;
+
+namespace Meezi.API.Tests.Integration;
+
+[Collection(nameof(MeeziIntegrationCollection))]
+public class HealthIntegrationTests
+{
+    private readonly MeeziWebApplicationFactory _factory;
+
+    public HealthIntegrationTests(MeeziWebApplicationFactory factory) => _factory = factory;
+
+    [Fact]
+    public async Task Health_ReturnsOk()
+    {
+        using var client = _factory.CreateClient();
+        var response = await client.GetAsync("/health");
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+    }
+}

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

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

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

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+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.AspNetCore.TestHost;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Meezi.API;
+using Meezi.Infrastructure.Data;
+
+namespace Meezi.API.Tests.Integration;
+
+public class MeeziWebApplicationFactory : WebApplicationFactory<Program>
+{
+    protected override IHost CreateHost(IHostBuilder builder)
+    {
+        var app = Program.BuildWebApplication(
+            Array.Empty<string>(),
+            ConfigureTestingBeforeServices,
+            ConfigureTestingAfterServices);
+        app.StartAsync().GetAwaiter().GetResult();
+        return app;
+    }
+
+    private static void ConfigureTestingBeforeServices(WebApplicationBuilder webBuilder)
+    {
+        webBuilder.Environment.EnvironmentName = "Testing";
+        webBuilder.WebHost.UseTestServer();
+        webBuilder.Configuration.AddInMemoryCollection(new Dictionary<string, string?>
+        {
+            ["Testing:Enabled"] = "true",
+            ["Testing:SkipSeed"] = "true",
+            ["RUN_MIGRATIONS"] = "false",
+            ["ConnectionStrings:Redis"] = "127.0.0.1:6379"
+        });
+    }
+
+    private static void ConfigureTestingAfterServices(WebApplicationBuilder webBuilder)
+    {
+        var dbDescriptor = webBuilder.Services.SingleOrDefault(d =>
+            d.ServiceType == typeof(DbContextOptions<AppDbContext>));
+        if (dbDescriptor is not null)
+            webBuilder.Services.Remove(dbDescriptor);
+
+        webBuilder.Services.AddDbContext<AppDbContext>(options =>
+            options.UseInMemoryDatabase("meezi_test_db"));
+    }
+}