Add IconSelect for filter types, audio modes, engine descriptions; fix scroll flash

- Filter type picker: IconSelect with 3-column grid, auto-add on select, removed redundant + button
- Audio mode picker: IconSelect with SVG visualizations for RMS/Peak/Beat
- Capture engine grid: added per-engine icons and localized descriptions
- Fixed scroll flash during icon grid open animation (settled class after transitionend)

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

server/src/wled_controller/static/css/components.css

@@ -522,6 +522,9 @@ textarea:focus-visible {
     opacity: 1;
     margin-top: 6px;
 }
+.icon-select-popup.open.settled {
+    overflow-y: auto;
+}
 
 .icon-select-grid {
     display: grid;