FEAT-13: SaleContract + BreederSettings entities (additive migration, join table justified in code docs), /contracts + /settings/breeder-profile Minimal-API endpoints w/ Abgabe-completion transaction + SQLite-backed endpoint round-trip tests (21/21)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

GerbilManager.Tests/ApiFactory.cs

@@ -0,0 +1,61 @@
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.Data.Sqlite;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+
+namespace GerbilManager.Tests;
+
+/// <summary>
+/// FEAT-13: In-Memory-Test-Host für Endpoint-Round-Trips. Ersetzt die
+/// Aspire/Npgsql-Registrierung durch SQLite in-memory (eine offene Verbindung
+/// hält die DB am Leben), Umgebung "Testing" überspringt Database.Migrate()
+/// (Npgsql-Migrationen laufen nicht auf SQLite) — Schema via EnsureCreated,
+/// inklusive der HasData-Seeds (73 Farbschläge + Zuchtprofil-Singleton).
+/// Vertrags-Dateien landen in einem Temp-Ordner, der mit dem Host stirbt.
+/// </summary>
+public sealed class ApiFactory : WebApplicationFactory<Program>
+{
+    private readonly SqliteConnection _connection = new("DataSource=:memory:");
+
+    public string ContractRoot { get; } =
+        Path.Combine(Path.GetTempPath(), $"gerbil-contract-tests-{Guid.NewGuid():N}");
+
+    protected override void ConfigureWebHost(IWebHostBuilder builder)
+    {
+        builder.UseEnvironment("Testing");
+        // Dummy, damit Aspires AddNpgsqlDbContext beim Host-Aufbau zufrieden ist;
+        // die eigentliche Registrierung wird unten durch SQLite ersetzt.
+        builder.UseSetting("ConnectionStrings:gerbilmanager",
+            "Host=localhost;Database=test;Username=test;Password=test");
+        builder.UseSetting("Contracts:RootPath", ContractRoot);
+
+        builder.ConfigureServices(services =>
+        {
+            // EF 9+: AddDbContext registriert die Provider-Konfiguration als
+            // IDbContextOptionsConfiguration<T> — ohne deren Entfernung blieben
+            // Npgsql UND SQLite registriert (ein Provider pro ServiceProvider).
+            services.RemoveAll<Microsoft.EntityFrameworkCore.Infrastructure.IDbContextOptionsConfiguration<ApplicationContext>>();
+            services.RemoveAll<DbContextOptions<ApplicationContext>>();
+            services.RemoveAll<ApplicationContext>();
+
+            _connection.Open();
+            services.AddDbContext<ApplicationContext>(o => o.UseSqlite(_connection));
+
+            using var provider = services.BuildServiceProvider();
+            using var scope = provider.CreateScope();
+            scope.ServiceProvider.GetRequiredService<ApplicationContext>().Database.EnsureCreated();
+        });
+    }
+
+    protected override void Dispose(bool disposing)
+    {
+        base.Dispose(disposing);
+        if (disposing)
+        {
+            _connection.Dispose();
+            if (Directory.Exists(ContractRoot)) Directory.Delete(ContractRoot, recursive: true);
+        }
+    }
+}