Add brp-d100 rule-pack (Basic Roleplaying roll-under): fumble on 100,
critical <= skill/20, special <= skill/5, success <= skill — bands
transcribed from the Continuum Day One console's verdict() logic.
Register it and switch day-one meta.system from coc-d100 to brp-d100.
tests/dice/brp-d100.test.js covers the ladder, low-skill rounding, and
the fumble-only-on-100 edge. 147 tests pass.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
