Fix M2 interior lighting and carpet sliding

- M2 interior darkening now uses global player-inside-WMO flag instead
  of per-instance queries that were unreliable
- Fix carpet/rug sliding by skipping lateral collision push when player
  is standing on top of any stepable low object, not just platforms

include/rendering/m2_renderer.hpp

@@ -22,7 +22,6 @@ namespace rendering {
 
 class Shader;
 class Camera;
-class WMORenderer;
 
 /**
  * GPU representation of an M2 model
@@ -277,10 +276,10 @@ public:
     }
     void clearShadowMap() { shadowEnabled = false; }
 
-    void setWMORenderer(WMORenderer* wmo) { wmoRenderer = wmo; }
+    void setInsideInterior(bool inside) { insideInterior = inside; }
 
 private:
-    WMORenderer* wmoRenderer = nullptr;
+    bool insideInterior = false;
     pipeline::AssetManager* assetManager = nullptr;
     std::unique_ptr<Shader> shader;