Update LoadSystemFonts function to clarify Linux compatibility

- Added a comment to indicate that the LoadSystemFonts function is intended for loading Linux system fonts into ImGui.
- Maintained the function for compatibility while ensuring it does not perform any operations on Linux, as system font loading is now handled by NFD (Native File Dialog).

src/app/core/platform/font_loader.cc

@@ -130,10 +130,13 @@ absl::Status ReloadPackageFont(const FontConfig& config) {
   return absl::OkStatus();
 }
 
+#ifdef __linux__
 void LoadSystemFonts() {
+  // Load Linux System Fonts into ImGui
   // System font loading is now handled by NFD (Native File Dialog)
   // This function is kept for compatibility but does nothing
 }
+#endif
 
 }  // namespace core
 }  // namespace yaze