fix: align floating actions and repair experimental publishingSquash f2457445 and 5c597eab while preserving floating-action placement and native-symbol artifact removal. Publish experimental APKs as prerelease assets to keep the Pages deployment below its size limit.Also clamp FAB bottom padding to non-negative values. Host-inset screens reserve the bottom overlay outside the entry, so subtracting Scaffold's 16dp FAB spacing from a zero clearance previously passed -16dp to Compose and crashed during layout.