Fix notification comment query, status title, and is-hidden visibility

notifications.php: comment notifications never fired because the query
used action_type='comment'/entity_type='ticket' but logCommentCreate
logs action_type='create'/entity_type='comment'. Fix query to match
actual log format and extract ticket_id from details JSON.

notifications.php: status change notification titles always showed
"? → ?" because code read details.old_value/new_value but logTicketUpdate
stores the delta as {"status": {"from": ..., "to": ...}}.

base.css: move .is-hidden to base.css (global) — it was only defined in
ticket.css, so on the dashboard the ticket-preview popup had no hide
rule applied and was visible in the DOM at all times.

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

assets/css/ticket.css

@@ -203,8 +203,7 @@ body.edit-mode .editable-metadata {
 }
 
 /* ── Visibility groups toggle ────────────────────────────────── */
-.ticket-visibility-groups.is-hidden,
-.is-hidden { display: none !important; }
+.ticket-visibility-groups.is-hidden { display: none !important; }
 
 /* ── Page header utility ─────────────────────────────────────── */
 .lt-page-header {