themeBar.ts: the sum of the whole labels (each in its own computed font, via canvas
measureText, so a hidden label still counts), icons, paddings and gaps against the
nav's room, with 16px hysteresis; writes html[data-wb-bar=labels|icons] on nav
resize, font loads and window resize. No width breakpoint decides it any more.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
