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>

GerbilManagerWebAPI/Program.cs

@@ -51,8 +51,13 @@ app.MapOpenApi();
 app.MapScalarApiReference();
 
 // Apply EF migrations at startup (no-op if schema is current; safe for single-instance deploy).
-using (var scope = app.Services.CreateScope())
+// Unter "Testing" übersprungen: die Endpoint-Tests laufen auf SQLite in-memory
+// (EnsureCreated) — die Npgsql-Migrationen sind dort nicht anwendbar.
+if (!app.Environment.IsEnvironment("Testing"))
+{
+    using var scope = app.Services.CreateScope();
     scope.ServiceProvider.GetRequiredService<ApplicationContext>().Database.Migrate();
+}
 
 app.UseCors(LanCorsPolicy);
 
@@ -67,5 +72,10 @@ app.MapWeightRecordEndpoints();
 app.MapInbreedingEndpoints();
 app.MapPhotoEndpoints();
 app.MapSaleAdEndpoints();
+app.MapContractEndpoints();
+app.MapSettingsEndpoints();
 
 app.Run();
+
+// Sichtbarer Programmtyp für WebApplicationFactory<Program> (Endpoint-Tests).
+public partial class Program { }