v0.39.0

Added

• GUTTER_DEFAULT, GUTTER_NARROW_DEFAULT and GUTTER_NARROW_BREAKPOINT from @nimblebrain/synapse/host. The same values @nimblebrain/synapse/ui exports ("1.5rem", "1rem", 640), from the entry that does not depend on React, so a host without React can hold its own breakpoint and values equal to the kit's. 0.38.0 said a host could test its values against these, but exported them only from /ui, whose entry imports React; this release makes that possible. /ui still exports them.