Some improvements, added cutscene stub

src/navigation/PathFinder.h

@@ -50,6 +50,7 @@ public:
 
     void addObstaclePolygon(const ObstaclePolygon& polygon);
     bool saveConfig(const std::string& path) const;
+    bool saveGrid(const std::string& path) const;
 
 private:
 
@@ -72,6 +73,7 @@ private:
     std::vector<NavigationArea> areas;
 
     void loadConfig(const std::string& configPath, const std::string& zipPath);
+    bool loadGrid(const std::string& path, const std::string& zipPath);
     void resetGridBounds();
     void rebuildWalkableGrid();
     void markAvailableAreasWalkable();