Promoted 14 new tokens (--accent-hover, --signal-{good,bad,warn}-hover,
--accent-bright, --thumb-black, --overlay, --shadow, --ease-out-{quart,expo},
--dur-{fast,normal,slide}, --z-topbar) and substituted every raw oklch /
cubic-bezier / hardcoded z-index occurrence in the 12 primitive files.
cubic-bezier appearances dropped from 8 files to 0 (only in tokens.css).
Bundle byte count: 138 KB -> 139 KB. Visual regression: zero (smoke page
still renders identically).
