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/DashboardView.php

@@ -1269,7 +1269,7 @@ if (advForm) advForm.addEventListener('submit', performAdvancedSearch);
           (age ? '<div class="lt-kv-row"><span class="lt-kv-label">Age</span><span class="lt-kv-value">' + esc(age) + '</span></div>' : '') +
         '</div>' +
       '</div>' +
-      '<p class="lt-text-muted lt-text-xs" style="text-align:center">Click "Open Full Ticket" for description, comments &amp; attachments.</p>';
+      '<p class="lt-text-muted lt-text-xs lt-text-center">Click "Open Full Ticket" for description, comments &amp; attachments.</p>';
 
     lt.rightDrawer.open('ticketPreviewDrawer');
   }