epic: refactor SDL2_Renderer usage to IRenderer and queued texture rendering

- Updated the testing guide to clarify the testing framework's organization and execution methods, improving user understanding.
- Refactored CMakeLists to include new platform-specific files, ensuring proper integration of the rendering backend.
- Modified main application files to utilize the new IRenderer interface, enhancing flexibility in rendering operations.
- Implemented deferred texture management in various components, allowing for more efficient graphics handling and improved performance.
- Introduced new methods for texture creation and updates, streamlining the rendering process across the application.
- Enhanced logging and error handling in the rendering pipeline to facilitate better debugging and diagnostics.

src/app/editor/dungeon/dungeon_object_selector.cc

@@ -90,7 +90,9 @@ void DungeonObjectSelector::DrawObjectRenderer() {
         auto preview_bitmap = std::move(preview_result.value());
         if (preview_bitmap.width() > 0 && preview_bitmap.height() > 0) {
           preview_bitmap.SetPalette(preview_palette_);
-          core::Renderer::Get().RenderBitmap(&preview_bitmap);
+          // Queue texture creation via Arena's deferred system
+          gfx::Arena::Get().QueueTextureCommand(
+              gfx::Arena::TextureCommandType::CREATE, &preview_bitmap);
           object_canvas_.DrawBitmap(preview_bitmap, preview_x, preview_y, 1.0f, 255);
         } else {
           // Fallback: Draw primitive shape