fix: accept app arguments in user_preference_dir - #531

Differential check of the 54 module-level *_dir / *_path functions against the PlatformDirs properties they wrap: 0 value divergences in 12,960 comparisons, and 8 reach gaps. All 8 are user_preference_dir and user_preference_path.

Neither takes arguments, so neither can pass the app name or the version that the property acts on:

>>> platformdirs.user_preference_dir()
'/Users/me/Library/Preferences'
>>> platformdirs.PlatformDirs("MyApp", version="1.0").user_preference_dir
'/Users/me/Library/Preferences/MyApp/1.0'
>>> platformdirs.user_preference_dir("MyApp", version="1.0")
TypeError: user_preference_dir() takes 0 positional arguments but 2 were given

macOS appends the app name and version to ~/Library/Preferences. On the other three platforms user_preference_dir resolves to user_config_dir, which is app scoped as well. Either way the function can only return the unscoped base directory.

#491 added these two in one batch with app independent helpers such as user_fonts_dir, and the zero argument shape carried over to the one member of the batch it does not suit.

This gives both the signature of user_config_dir. Defaults are unchanged, so a no-argument call returns what it returns today.

The test asserts the invariant over every getter in PROPS: where the property varies with appname and version, the function must accept them. Reverting __init__.py fails it for user_preference_dir alone; the other 26 parametrizations pass either way, as pins.

Testing: full suite on macOS with 3.14, 1032 passed. The four test_compatibility[site_data_dir-*] failures reproduce on a clean origin/main worktree. Pinned ruff v0.16.4 is clean. Windows and Linux legs unrun here.

Drafted with Claude Code (Claude Opus 5). Not yet reviewed by a human; @dylanpulver will review before this is treated as ready.