Fix ascii-frame-outer blink: remove compositor layer thrashing on hover

Four root causes removed:
- body { transition: all } — forced browser to check all CSS properties
  on every hover event across the entire page
- a:not(.btn)::after underline: width+box-shadow transition replaced with
  opacity transition — width repaints paint layer, box-shadow forced parent
  section repaint; opacity is GPU-composited and doesn't repaint ancestors
- .ticket-link:hover { transform: translateX } — created/destroyed GPU
  compositor layer on every ticket ID hover; removed, scoped transition
  to specific non-layout properties
- .btn:hover { transform: translateY } in ticket.css — same layer issue

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

assets/css/ticket.css

@@ -564,7 +564,6 @@ textarea.editable {
 }
 
 .btn:hover {
-    transform: translateY(-2px);
     box-shadow: 0 2px 4px rgba(0,0,0,0.1);
 }