* Replace the docs theme identity select with a matching pill control The theme identity picker was a raw native <select>, the only native form control on the docs surface, squeezed to ~200px in the sidebar footer and truncating "Tactile". Add a text-label segmented toggle group alongside the existing icon-only one, sharing the same pill shape, height, and focus treatment as the colour-mode group beside it, and use it for theme identity in both the sidebar footer and the playground header. Also give system colour mode a settings-gear glyph so it no longer collides with the monitor icon used for the Desktop viewport option. * Swap the system colour-mode glyph for a half-filled circle A settings cog reads as "open theme options", not "follow the operating system" — a misleading glyph, not just an ambiguous one. Replace it with the conventional split-circle contrast mark (one half filled, one half outline), which reads as "either of these two, decided for you". Matches the existing icon set's outline conventions (24x24 viewBox, currentColor stroke) apart from the filled half the mark requires.