Add unit tests for department lane dynamic image overrides and introduce classes for self-serve signal and virtual hardware management

- Add `DepartmentLaneDynamicImageRouteTest` to verify dynamic image preview handling for studio lanes.
- Introduce `selfserve_machine_signal` class to standardize signal normalization, recording, and gateway signal management workflows.
- Add `selfserve_virtual_hardware` class to handle virtual hardware configurations, including gateway and binding management.
- Enhance structure with auxiliary methods for payload normalization, workspace merging, and validation warnings.

services/nginx/app/tests/Unit/DynamicImages/DepartmentLaneDynamicImageRouteTest.php

@@ -0,0 +1,11 @@
+<?php
+
+it('allows studio lane dynamic image previews to override the saved image id', function (): void {
+    $content = file_get_contents(app_path('routes/departmentLanesRoute.php'));
+
+    expect($content)->not->toBeFalse();
+    expect($content)->toContain("isRequestParameterSet('dynamic_image_id')");
+    expect($content)->toContain("\$dynamic_image_override = \$response->getRequestParameter('dynamic_image_id')");
+    expect($content)->toContain("self::requireMinValue(\$dynamic_image_id, 1)");
+    expect($content)->toContain("switch (\$dynamic_image_id)");
+});