Text-only via buttonClass; label + icon via labelledBtnHtml /
actionButtonHtml (detail-panel.js); icon-only via btn-icon.
All patterns live in the Aurora UI shell framework, not host-specific markup.
Text only
Label and icon
Uses btn__icon + LABELLED_BTN_ICON_OPTS from the framework.
Modal Save/Create buttons add the floppy icon via openModal (same shell helper).
Icon only
Row actions and compact chrome use btn-icon.