Fix leading-zero ticket ID handling across API and UI

- dashboard.js: use String(cb.value) instead of parseInt() in
  getSelectedTicketIds() so zero-padded IDs like 000123456 are
  preserved when sent to bulk_operation.php
- DashboardView.php: remove (int) cast on data-ticket-id attribute
  for quick-status button; was stripping leading zeros
- TicketView.php: remove (int) cast on export URL ticket_id param
- update_ticket.php: preserve ticket_id as string via trim((string)...)
- add_comment.php: preserve ticket_id as string; validate with
  ctype_digit instead of (int) cast so comments are stored with the
  canonical zero-padded ID matching the tickets table
- export_tickets.php: validate singleId as string to avoid stripping
  leading zeros in the export endpoint
- notifications.php: preserve ticket_id strings in URLs and ticket
  ownership checks; index myTicketIds by both int and string forms
  for robust lookup regardless of how audit_log stored the ID
- TicketController.php: fix inline dependency insert — column was
  wrong (depends_on_ticket_id → depends_on_id) and bind types were
  wrong ("iii" → "ssi"); feature was silently broken

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

api/add_comment.php

@@ -65,8 +65,8 @@ try {
         throw new Exception("Invalid JSON data received");
     }
 
-    $ticketId = isset($data['ticket_id']) ? (int)$data['ticket_id'] : 0;
-    if ($ticketId <= 0) {
+    $ticketId = isset($data['ticket_id']) ? trim((string)$data['ticket_id']) : '';
+    if (!ctype_digit($ticketId) || (int)$ticketId <= 0) {
         http_response_code(400);
         ob_end_clean();
         header('Content-Type: application/json');