Movement: player-like paths, no more cliff shortcuts

Autonomous players now compute a route a human could take: no slopes beyond 50°, and steep slopes are avoided whenever possible.

The core navigation mesh allows slopes up to 60° (meant for creatures); a player character slides beyond about 50°. Autonomous players were therefore climbing slopes no human could.
New route finding (FreeWillPath): a Detour query with a filter that excludes overly steep polygons and makes 35–50° slopes up to 3 times more expensive.
Path points are placed on the ground every 4 m along the path corners, with each leg capped at 160 m before recomputing.
The core path remains as a fallback (swimming, start off the mesh, destination only reachable through a steep slope).
The final straight-line approach off the mesh is reduced from 15 m to 6 m.
First measurements: 94% of tracked trips use the new path, with no increase in stuck events.