refactor: Integrate PlatformPaths for configuration directory management

- Replaced direct calls to GetConfigDirectory with PlatformPaths::GetConfigDirectory across multiple files to standardize configuration directory access.
- Updated RecentFilesManager, EditorManager, and various agent components to handle potential errors when retrieving the configuration directory.
- Enhanced file loading functions to utilize the new LoadFileFromConfigDir method for improved clarity and error handling.
- Introduced new methods in file_util.h for better file management practices, leveraging std::filesystem for cross-platform consistency.

src/util/util.cmake

@@ -17,6 +17,7 @@ set(YAZE_UTIL_SRC
   util/log.cc
   util/platform_paths.cc
   util/file_util.cc
+  util/platform_paths.cc
 )
 
 add_library(yaze_util STATIC ${YAZE_UTIL_SRC})