fix(editor): add M2 render diagnostics to Info panel for NPC debugging

- Info panel now shows M2 renderer stats: model count, instance count,
  draw call count — visible in real-time to diagnose NPC rendering issues
- When placing NPCs: if models=0/instances=0, the model failed to load
  If models>0 but draws=0, it's a culling/frame-sync issue
  If draws>0, the model IS rendering but may be too small to see

tools/editor/editor_app.hpp

@@ -49,6 +49,7 @@ public:
     NpcPresets& getNpcPresets() { return npcPresets_; }
     AssetBrowser& getAssetBrowser() { return assetBrowser_; }
     rendering::TerrainRenderer* getTerrainRenderer();
+    rendering::M2Renderer* getM2Renderer() { return viewport_.getM2Renderer(); }
     pipeline::AssetManager* getAssetManager() { return assetManager_.get(); }
 
     const std::string& getLoadedMap() const { return loadedMap_; }