fix: various inline style cleanup, a11y improvements, and bind_param bug

- Replace style="text-align:center" with .lt-text-center utility class in
  WorkflowDesignerView, CustomFieldsView, error_403, error_404, DashboardView JS string
- Replace style="margin-top:..." with .lt-mt-sm utility in WorkflowDesignerView
- Switch comment-edit-raw data-store textareas to .is-hidden class (TicketView PHP
  + JS-rendered; ticket.js template literal) — these are never shown, only read via .value
- Add aria-describedby="visibilityGroupsHint" + id on hint <p> in CreateTicketView
- Fix bind_param type string bug in manage_workflows.php PUT handler: 'ssiiiii' → 'ssiiii'
  (7 type chars for 6 params caused binding error on workflow transition updates)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

views/error_403.php

@@ -10,7 +10,7 @@ include __DIR__ . '/../views/layout_header.php';
 <div class="lt-frame" style="max-width:32rem;margin:4rem auto">
   <span class="lt-frame-bl">╚</span><span class="lt-frame-br">╝</span>
   <div class="lt-section-header lt-text-danger">[ 403 ] ACCESS DENIED</div>
-  <div class="lt-section-body" style="text-align:center">
+  <div class="lt-section-body lt-text-center">
     <p class="lt-text-muted lt-mb-md">You do not have permission to access this resource.</p>
     <a href="/" class="lt-btn lt-btn-primary">&larr; Dashboard</a>
   </div>