Movement & Terrain Interaction

[M1thieu]

Implement terrain-based adjustments to creature movement dynamics.

• Add logic to slow movement on rough or steep terrain.
• Restrict movement on impassable surfaces (e.g., cliffs or water for non-swimmers).
• Test interactions between different terrain types and movement efficiency.

Not planned if the DEFORM base ain't ready #76 yet considered

• Use terrain properties from the Terrain System (WIP) to influence movement.