* fix(js): implement CSS.supports() feature detection
CSS.supports() was a stub that always returned false. Sites that
feature-detect CSS support (e.g. CSS.supports('display','flex'))
treated the engine as lacking flexbox and redirected to their
"unsupported browser" page, so the SPA never rendered.
Implement both call signatures — supports(property, value) and
supports(conditionText) — and return true for well-formed standard
CSS declarations, matching modern browser behaviour. Malformed input
(empty property/value, or a condition string with no colon) returns
false.
* Revert CSS.escape change, keep PR scoped to CSS.supports
The escape stub was switched to String(s), which is unrelated to the
feature-detection fix and still not a spec CSS.escape. Restore the original
stub so this PR only touches CSS.supports.
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Co-authored-by: SGavrl <[email protected]>
