tune(bot): raise cooldown scale factor from 200 to 400
frequent bufos weren't getting penalized hard enough — at 3.4% of
matches, is-up-to-something only had a 147min cooldown. doubling the
scale factor makes the quadratic curve steeper.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>