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>

api/manage_workflows.php

@@ -120,7 +120,7 @@ try {
             $stmt = $conn->prepare("UPDATE status_transitions SET
                                     from_status = ?, to_status = ?, requires_comment = ?, requires_admin = ?, is_active = ?
                                     WHERE transition_id = ?");
-            $stmt->bind_param('ssiiiii',
+            $stmt->bind_param('ssiiii',
                 $data['from_status'],
                 $data['to_status'],
                 $data['requires_comment'] ?? 0,