PR refactors multiple files by replacing os.path functions such as os.path.join, os.path.basename, and os.path.exists, etc. with pathlib.Path.

Key changes:

• replaced os.path.join() with Path() / "filename"
• used .name instead of os.path.basename() for cleaner path extraction
• switched from os.path.exists() to Path.exists() for improved clarity
• updated os.remove() calls to Path.unlink() for better deletion handling
• refactored loops using Path.iterdir() instead of os.listdir()

this is going to fix #1229 (probably), because:

• LIBDIR.parent / "mods" correctly moves up one level from lib/tuxemon to the parent directory (exe.win-amd64-3.12), then joins "mods" to it
• ensures that mods is a sibling of lib, not mistakenly placed inside it
• using pathlib ensures compatibility across different OS without requiring os.path.join or normalization