Fix PHP parse error and CSS/JS follow-on fixes

- DashboardView.php: fix PHP parse error on line 456/472/473/474 caused by
  escaped double-quotes {$row[\"key\"]} inside double-quoted echo strings;
  replaced with safe string concatenation . $row['key'] .
- ticket.css: fix status-select hover/focus border rgba(white) → terminal palette
- ticket.js: add null guards to addComment, togglePreview, updatePreview,
  toggleMarkdownMode, and addDependency element lookups

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

assets/css/ticket.css

@@ -1367,12 +1367,12 @@ body.dark-mode .timeline-date {
 
 .status-select:hover {
     opacity: 0.9;
-    border-color: rgba(255, 255, 255, 0.3);
+    border-color: rgba(0, 255, 65, 0.4);
 }
 
 .status-select:focus {
     outline: none;
-    border-color: rgba(255, 255, 255, 0.5);
+    border-color: var(--terminal-amber);
 }
 
 /* Status colors for dropdown */