refactor(framemode): unify connected surface chrome via SDF pipeline

- Shadow system rewrite with SDF quads
- Replace ConnectedShape/layer FBOs w/frame & chrome SDF shaders
- Improve frame blur performance
- Plugin performance gate

.agents/skills/dms-plugin-dev/references/widget-plugin-guide.md

@@ -235,7 +235,7 @@ Conditionally show/hide the bar pill:
 ```qml
 PluginComponent {
     visibilityCommand: "pgrep -x myapp"
-    visibilityInterval: 5000  // check every 5 seconds
+    visibilityInterval: 5  // seconds between checks; polling pauses while the bar is hidden
 }
 ```