Add M2 global sequence animation, smoke UV scroll, and fix WMO floor detection

- Parse global sequence durations from M2 binary and use them in bone
  interpolation so torches, candles, and other env doodads animate.
- Add UV scroll shader effect for smoke models (HouseSmoke, SmokeStack)
  as a workaround for unimplemented M2 particle emitters.
- Tighten WMO floor probe heights to prevent multi-story buildings from
  returning the wrong floor, fixing player clipping through inn floors
  and camera locking onto the second floor.
- Use player ground level as reference for camera orbit floor collision
  so the camera doesn't fight upper floors in buildings.

include/pipeline/m2_loader.hpp

@@ -132,6 +132,7 @@ struct M2Model {
     // Skeletal animation
     std::vector<M2Bone> bones;
     std::vector<M2Sequence> sequences;
+    std::vector<uint32_t> globalSequenceDurations;  // Per-global-sequence loop durations (ms)
 
     // Rendering
     std::vector<M2Batch> batches;