Separate the jump execution (velocity, event, animation) from the
gate logic (respawn check, upmove threshold, jump-held check).
This prepares the code for QL features that need to trigger jumps
from contexts other than the normal ground jump path (step jump,
double jump, etc). No behavior change.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
