PySide6 Rewrite

Rebuilt the launcher UI with PySide6 (Qt), replacing the old Tkinter interface for a modern and responsive design.
Added a thumbnail system: low-resolution thumbnails are auto-generated for faster game list loading, while the right-side detail view displays the full-resolution cover.
Settings now support thumb_dir and thumb_size for customizable thumbnail storage and resolution.

Version Note:

⚠️ No ROMs or copyrighted game artwork are included. Users must provide their own legally obtained files.