- Add mutex to AssetManager::loadTexture/loadDBC/fileExists to prevent
StormLib thread-safety races that silently fail texture reads; stop
caching texture load failures so transient errors are retried.
- Replace /unstuckgy DBC lookup (which used wrong coordinate transform)
with hardcoded safe locations per map.
- Widen WMO floor raycast from single grid cell to ±1 unit range query
to catch bridge/walkway triangles at cell boundaries.
- Tighten swept collision hit threshold (0.5 → 0.15) and grid query
margin (2.5 → 1.5) to prevent false-positive wall pushes.
- Tighten post-wall-push Z snap lower bound (-1.0 → -0.3) to prevent
gradual floor sinking.
