Add Comprehensive Dungeon Editor Design Plan

- Introduced a detailed design plan document for the Yaze Dungeon Editor, outlining the current architecture, main components, and core systems.
- Documented identified issues and applied fixes, including crash prevention and UI simplification, along with a roadmap for future development phases.
- Enhanced clarity on the implementation guidelines, testing strategies, and performance considerations to support ongoing development efforts.
- Established a structured approach for new developers to understand the codebase and contribute effectively to the project.

src/app/editor/dungeon/dungeon_object_selector.cc

@@ -127,6 +127,20 @@ void DungeonObjectSelector::DrawObjectRenderer() {
   }
 }
 
+void DungeonObjectSelector::Draw() {
+  if (ImGui::BeginTabBar("##ObjectEditorTabBar")) {
+    if (ImGui::BeginTabItem("Graphics")) {
+      DrawRoomGraphics();
+      ImGui::EndTabItem();
+    }
+    if (ImGui::BeginTabItem("Editor")) {
+      DrawIntegratedEditingPanels();
+      ImGui::EndTabItem();
+    }
+    ImGui::EndTabBar();
+  }
+}
+
 void DungeonObjectSelector::DrawRoomGraphics() {
   const auto height = 0x40;
   room_gfx_canvas_.DrawBackground();