tui dashboard follows the browser's light/dark scheme
The tui dashboard now tracks the browser or OS color scheme. Each themeable token is a single light-dark(lightValue, darkValue) declaration under color-scheme: light dark, so the ghostty light and dark palettes live in one source of truth per token instead of a :root block shadowed by a @media (prefers-color-scheme: dark) override.
A <meta name="color-scheme" content="light dark"> in <head> lets the user agent settle on the scheme before CSS parses. That tag is the actual fix for webviews that rendered the light theme even in dark mode: the CSS already flipped correctly under an emulated dark scheme, so the bug was the host not advertising its scheme early enough.
Browsers without light-dark() (roughly 15% as of 2026) fall back to the classic dark override inside @supports not (color: light-dark(#000, #fff)). Verified with Playwright: emulated dark resolves --bg to #151515, light to #ececec.