ui: finish css state cleanup

TASKS.md

@@ -2,14 +2,14 @@
 
 ## Current
 
-### `feat/frontend-css-state-cleanup`
+### `feat/frontend-performance-polish`
 
 Status: in_progress
 
 DoD:
-- UI state visuals are driven by classes or semantic attributes instead of ad-hoc inline style mutation
-- button disabled/loading states do not rely on manual style toggles
-- wizard and workspace flows keep current behavior after state-class migration
+- repeated derived views are cached or precomputed instead of recalculated per render path
+- UI interaction handlers avoid unnecessary full rerenders for small state changes
+- performance changes keep current page behavior and pass existing smoke checks
 
 ## Next
 

apps/ui/js/settings.js

@@ -244,7 +244,7 @@ function bindSectionNavigation() {
   }, { threshold: 0.3 });
 
   document.querySelectorAll('[id^="section-"]').forEach(function (section) {
-    if (section.style.display !== 'none') {
+    if (!section.hidden) {
       observer.observe(section);
     }
   });