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/base.css

@@ -2341,6 +2341,7 @@ select option:checked {
 .lt-text-upper { text-transform: uppercase; letter-spacing: 0.1em; }
 
 .lt-hidden  { display: none !important; }
+.is-hidden  { display: none !important; }
 
 /* Skip navigation link — visible only on focus */
 .lt-skip-link {