Extend lt.time.ago() to ticket view, replace showToast with lt.toast

- Add data-ts attributes to TicketView.php: ticket created/updated
  header, comment dates (inner span to preserve edited indicator),
  and all activity timeline dates
- Add initRelativeTimes() to ticket.js using lt.time.ago(); runs on
  DOMContentLoaded and every 60s to keep relative times current
- Attachment dates now use lt.time.ago() with full date in title attr
  and ts-cell span for periodic refresh
- Replace all 11 showToast() calls in ticket.js with lt.toast.* directly,
  removing reliance on the backwards-compat shim for these paths
- Add span.ts-cell and td.ts-cell CSS to both dashboard.css and ticket.css:
  dotted underline + cursor:help signals the title tooltip is available

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

assets/css/ticket.css

@@ -1489,6 +1489,14 @@ body.dark-mode .editable {
     border-color: var(--border-color) !important;
 }
 
+/* ===== RELATIVE TIMESTAMP CELLS ===== */
+
+span.ts-cell {
+    cursor: help;
+    border-bottom: 1px dotted var(--text-muted);
+    text-decoration: none;
+}
+
 /* ===== RESPONSIVE DESIGN - TERMINAL EDITION ===== */
 
 /* Tablet and smaller */