Rename signature templates by removing underscores

Standardized template names in WorkflowController and WorkflowAddSignatureController for better consistency. Updated references and renamed template files accordingly.

src/Bundle/ChillMainBundle/Controller/WorkflowAddSignatureController.php

@@ -71,7 +71,7 @@ final readonly class WorkflowAddSignatureController
 
         return new Response(
             $this->twig->render(
-                '@ChillMain/Workflow/_signature_sign.html.twig',
+                '@ChillMain/Workflow/signature_sign.html.twig',
                 ['signature' => $signatureClient]
             )
         );