perf(electrobun): JS blink replaces CSS animation, 1.13% CPU (was 6.5%)

JS setInterval(500ms) toggles .blink-off class instead of CSS @keyframes.
WebKitGTK handles discrete class toggle efficiently (single repaint per toggle).
0.7% idle + 0.43% blink overhead = 1.13% total.

Comparison:
- CSS @keyframes: 6.5% (continuous compositor animation)
- JS class toggle: 1.13% (2 repaints/sec)
- No animation: 0.7% (baseline)
- Tauri (CSS): ~0% (browser compositor optimized)
- GPUI (custom Element): 2.17%

ui-electrobun/src/mainview/app.css

@@ -204,7 +204,11 @@ html, body {
 
 .status-dot.running {
   --dot-color: var(--ctp-green);
-  /* animation: pulse-dot 2s ease-in-out infinite; DISABLED for CPU test */
+  /* No CSS animation — JS timer toggles .blink-off class instead */
+}
+
+.status-dot.blink-off {
+  opacity: 0.3;
 }
 
 .status-dot.idle {
@@ -213,7 +217,6 @@ html, body {
 
 .status-dot.stalled {
   --dot-color: var(--ctp-peach);
-  /* animation: pulse-dot 1.4s ease-in-out infinite; DISABLED for CPU test */
 }
 
 @keyframes pulse-dot {