Fix persistent blink: scanline animation still active via base.css cascade

Root cause: removing 'animation' from dashboard.css body::before did NOT disable
the scanline — it just stopped overriding base.css which still had
'animation: scanline 8s linear infinite'. CSS cascade means the base.css value
remained active. Fixed by setting 'animation: none' explicitly in dashboard.css.

Also fix base.css (used by all pages including ticket page):
- Set body::before animation: none (removes GPU compositing layer from scanline)
- Change corner-pulse/subtle-pulse/pulse-glow/pulse-red keyframes from text-shadow
  and box-shadow animations to opacity (GPU composited, zero CPU repaint overhead)
- Change exec-running-pulse from box-shadow to opacity
- Remove box-shadow from .lt-table tr:hover, .lt-card:hover, .lt-stat-card:hover
- Remove text-shadow/box-shadow/transform from .lt-btn:hover and variants
- Remove text-shadow from a:hover

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

assets/css/dashboard.css

@@ -117,6 +117,7 @@ body::before {
     );
     pointer-events: none;
     z-index: var(--z-overlay);
+    animation: none;
 }
 
 /* Screen Flicker Effect */