computeTrends() classifies tests as stable-pass/stable-fail/flaky/
improving/degrading based on pass rate, flip count, and recent streak.
gstack eval trend shows sparkline table with --limit, --tier, --test
filters. Guard CLI main block with import.meta.main to prevent
execution on import.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Garry Tan