The server catalog ships bare glyph names, but the SPA grid preview
composed "fas home" instead of "fas fa-home" — every FA icon rendered
blank (the old curated lists carried the fa- prefix, so the regression
appeared with the catalog switch).
Item clicks move from per-element @click to a delegated panel handler
reading data-icon (immunity to DOM-replacing extensions/userscripts,
matching the PHP picker's pattern), and selecting now closes the
popover so the choice is visible in the field immediately.
