on MacOS using osascript instead of tk to avoid crash

[bpstudio]

Summary

Save, Load, and audio import currently create and destroy a new Tk root on every click. On macOS that conflicts with Pygame/SDL's Cocoa NSApplication singleton, so the file picker hangs or crashes.

This change:

• Uses the native macOS file dialog via osascript on Darwin
• Keeps a single persistent Tk root on Windows/Linux instead of create/destroy
• Routes Save, Load, and audio import through the same helper

On Windows/Linux: Save, Load, and audio import still open the Tk file picker

[GeorgiosPapadakis]

@JRYCodesYT Create a new branch, for example develop, where there you should handle Pull Requests (PRs) and test them. It will make the development more controllable.
The commit looks good btw. Good job @bpstudio !!

[bpstudio]

@JRYCodesYT @GeorgiosPapadakis yes, if there is a develop branch, I can modify the PRs to merge to there.

[GeorgiosPapadakis]

@bpstudio Yes @JRYCodesYT must handle that.