Refactor runtime bootstrap and ship control flows

apps/backend/Auth/Api/RegisterHandler.cs

@@ -0,0 +1,25 @@
+using FastEndpoints;
+
+namespace SpaceGame.Api.Auth.Api;
+
+public sealed class RegisterHandler(AuthService authService) : Endpoint<RegisterRequest, AuthSessionResponse>
+{
+    public override void Configure()
+    {
+        Post("/api/auth/register");
+        AllowAnonymous();
+    }
+
+    public override async Task HandleAsync(RegisterRequest request, CancellationToken cancellationToken)
+    {
+        try
+        {
+            await SendOkAsync(await authService.RegisterAsync(request, cancellationToken), cancellationToken);
+        }
+        catch (InvalidOperationException ex)
+        {
+            AddError(ex.Message);
+            await SendErrorsAsync(cancellation: cancellationToken);
+        }
+    }
+}