Fourth compiled-in shell theme (bread-theme/src/shell/builtin.rs). Stresses
four axes no existing theme touched:
- light surfaces (new tokens.light flag, swaps which of the fixed @bg/
@on-bg pair plays paper-surface vs ink — see Tokens::light's doc comment)
- bottom anchoring (bar.window.anchors = ["bottom", ...])
- segmented bar chrome (new bar_border = "segmented" value: the bar window
itself draws no fill/border, three slot-group pills draw their own)
- blur disabled per-theme ([compositor.*] blur = false everywhere)
Also: a new bottom_right surface anchor (manifest.rs + types.rs), since the
three existing anchor shapes all assume a top-anchored bar's satellites
belong in the top-right corner. tokens.accent2() gives the equaliser its
own accent independent of accent_from/accent_to.
