Variable SIDE_STEP_ANIMATIONConst

Side step animation (옆으로 스텝)

Lateral hip shift with trailing leg for quick evasion.

Animation phases:

1. Shift left (0.0s): Weight to left leg
2. Slide (0.15s): Right leg follows
3. Plant (0.25s): Both feet grounded
4. Reset (0.3s): Return to center

Duration: 300ms