Refactor DungeonCanvasViewer for enhanced rendering and object management

- Introduced new rendering methods for various object types including stairs, chests, doors, walls, pots, and sprites, improving visual representation in the dungeon canvas.
- Updated the DrawDungeonCanvas method to streamline object rendering and enhance graphics handling.
- Added detailed layer information overlay to provide context on room objects and sprites.
- Implemented object dimension calculations for walls to ensure accurate rendering based on size properties.
- Improved fallback rendering for objects without valid graphics, enhancing user experience during object placement and editing.

src/app/editor/dungeon/dungeon_object_selector.h

@@ -56,6 +56,10 @@ class DungeonObjectSelector {
     object_selected_callback_ = callback;
   }
   
+  void SetObjectPlacementCallback(std::function<void(const zelda3::RoomObject&)> callback) {
+    object_placement_callback_ = callback;
+  }
+  
   // Get current preview object for placement
   const zelda3::RoomObject& GetPreviewObject() const { return preview_object_; }
   bool IsObjectLoaded() const { return object_loaded_; }
@@ -65,6 +69,17 @@ class DungeonObjectSelector {
   void DrawObjectBrowser();
   void DrawCompactObjectEditor();
   void DrawCompactSpriteEditor();
+  
+  // Helper methods for primitive object rendering
+  ImU32 GetObjectTypeColor(int object_id);
+  std::string GetObjectTypeSymbol(int object_id);
+  void RenderObjectPrimitive(const zelda3::RoomObject& object, int x, int y);
+  
+  // AssetBrowser-style object selection
+  void DrawObjectAssetBrowser();
+  bool MatchesObjectFilter(int obj_id, int filter_type);
+  void CalculateObjectDimensions(const zelda3::RoomObject& object, int& width, int& height);
+  void PlaceObjectAtPosition(int x, int y);
   void DrawCompactItemEditor();
   void DrawCompactEntranceEditor();
   void DrawCompactDoorEditor();
@@ -96,6 +111,10 @@ class DungeonObjectSelector {
   
   // Callback for object selection
   std::function<void(const zelda3::RoomObject&)> object_selected_callback_;
+  std::function<void(const zelda3::RoomObject&)> object_placement_callback_;
+  
+  // Object selection state
+  int selected_object_id_ = -1;
 };
 
 }  // namespace editor