refactor(gui): reorganize background rendering and layout helpers

- Moved background rendering functionality from the editor to a dedicated GUI module, enhancing modularity and separation of concerns.
- Introduced layout helpers for consistent theme-aware sizing across the GUI, improving UI consistency and maintainability.
- Updated CMake configuration to reflect the new structure, ensuring proper linkage of the background renderer and layout helpers.

Benefits:
- Improved organization of GUI components, facilitating easier updates and enhancements.
- Enhanced user interface consistency through theme-aware layout management.

src/util/util.cmake

@@ -17,7 +17,7 @@ set(YAZE_UTIL_SRC
   util/log.cc
   util/platform_paths.cc
   util/file_util.cc
-  util/platform_paths.cc
+  util/hyrule_magic.cc  # Byte order utilities (moved from zelda3)
 )
 
 add_library(yaze_util STATIC ${YAZE_UTIL_SRC})