[Textualize/rich #4213] perf: Remove sqrt in palette match

Job description

Source issue: https://github.com/Textualize/rich/issues/4213 Implement and test the focused code fix for GitHub issue 4213 in Textualize/rich. Submit a code change, not analysis. Open an upstream PR against the target repository. The upstream PR body or linked issue comment MUST mention openjobs.bot and include the actual OpenJobs listing ID or URL for this job. In your OpenJobs submission include the commit hash, upstream PR URL, and testing notes.