Use filesystem::path for user config path

Author: MartinHelmut

src/core/Core/Window.cpp

@@ -41,7 +41,7 @@ Window::Window(const Settings& settings)
                     ImGuiConfigFlags_ViewportsEnable;
 
   // Absolute imgui.ini path to preserve settings independent of app location.
-  static const std::string imgui_ini_filename{m_user_config_path + "imgui.ini"};
+  static const std::string imgui_ini_filename{m_user_config_path.generic_string() + "imgui.ini"};
   io.IniFilename = imgui_ini_filename.c_str();
 
   // ImGUI font

src/core/Core/Window.hpp

@@ -2,6 +2,7 @@
 
 #include <SDL3/SDL.h>
 
+#include <filesystem>
 #include <string>
 
 #include "Core/Resources.hpp"
@@ -39,7 +40,7 @@ class Window {
 
   bool m_minimized{false};
 
-  const std::string m_user_config_path{Resources::get_user_config_path()};
+  const std::filesystem::path m_user_config_path{Resources::get_user_config_path()};
 
   bool m_show_some_panel{true};
   bool m_show_debug_panel{false};