Farvist v0.10.0 — autoprefixer + compatibility

Shipped CSS is now autoprefixed. A PostCSS + Autoprefixer step (npm run build:prefix, chained into build:all) runs against a browserslist target, adding the vendor prefixes the hand-written source missed (-webkit-user-select, -moz-column-gap for Firefox flex-gap, -moz-appearance, -moz-placeholder) while preserving Safari's -webkit-backdrop-filter. Plus a documented browser-support matrix in the README + docs: baseline Chrome/Edge 111+, Safari 16.4+, Firefox 113+ (early 2023), with graceful degradation for @layer, backdrop-filter, color-mix and field-sizing. No source rewrites; @layer cascade + a11y verified unchanged. Live: https://farvist.com