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/dashboard.css

@@ -4642,6 +4642,20 @@ table td:nth-child(4) {
     border-top: 1px solid var(--terminal-green);
 }
 
+/* ===== RELATIVE TIMESTAMP CELLS ===== */
+
+/* Inline spans with data-ts show relative time; title attr has the full date */
+span.ts-cell {
+    cursor: help;
+    border-bottom: 1px dotted var(--text-muted);
+    text-decoration: none;
+}
+
+/* Table cells with data-ts — no underline on full td, just cursor hint */
+td.ts-cell {
+    cursor: help;
+}
+
 /* ===== ENHANCED MOBILE RESPONSIVE STYLES ===== */
 
 /* Table wrapper - horizontal scroll when table overflows container */