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/templates/modals/pp-template.html

@@ -21,7 +21,6 @@
                     <select id="pp-add-filter-select" class="pp-add-filter-select">
                         <option value="" data-i18n="filters.select_type">Select filter type...</option>
                     </select>
-                    <button type="button" class="pp-add-filter-btn" onclick="addFilterFromSelect()" title="Add Filter">+</button>
                 </div>
 
                 <div class="form-group">