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/gui/style.cc

@@ -5,7 +5,7 @@
 #include "util/file_util.h"
 #include "app/gui/theme_manager.h"
 #include "app/editor/ui/background_renderer.h"
-#include "app/core/platform/font_loader.h"
+#include "app/platform/font_loader.h"
 #include "app/gui/color.h"
 #include "app/gui/icons.h"
 #include "imgui/imgui.h"
@@ -1293,7 +1293,7 @@ void DrawFontManager() {
   static bool font_selected = false;
 
   ImGui::Text("Loaded fonts");
-  for (const auto &loaded_font : core::font_registry.fonts) {
+  for (const auto &loaded_font : font_registry.fonts) {
     ImGui::Text("%s", loaded_font.font_path);
   }
   ImGui::Separator();