Three root causes, all fixed:
1. Icon buttons were created with setAttribute('onclick', ...) in
populateIconGrid, but selectIcon is module-scoped (not on window),
so clicking threw ReferenceError. Switch to addEventListener with
a closure. Icon search/focus used plain oninput/onfocus attributes
with the same problem — convert to Alpine @input/@focus.
2. selectColor's highlight selector queried [onclick="selectColor(...)\]