The `endswith(ts)` check in `get_column_groups` matched columns
incorrectly when time shifts shared a numeric suffix — e.g.
"metric__22 weeks ago".endswith("2 weeks ago") returned True,
causing columns to be misclassified. Use `endswith(TIME_COMPARISON + ts)`
to include the "__" separator in the match.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
