uv

5aeaa31a - Set `XDG_CONFIG_HOME` in `with_real_home()` to isolate test config (#17456)

Set `XDG_CONFIG_HOME` in `with_real_home()` to isolate test config (#17456) The `with_real_home()` method sets `HOME` to the real home directory, which is required for tests that use the macOS keychain for authentication. However, this causes a problem: when `HOME` is set but `XDG_CONFIG_HOME` is not, uv resolves the config directory to `$HOME/.config/uv` per the XDG specification. This means tests would read the user's real configuration files (like `.python-version` or `uv.toml`), which can override test-specified settings and cause failures. This PR sets `XDG_CONFIG_HOME` to the test's isolated config directory in `with_real_home()`, ensuring that even when the real HOME is needed for keychain access, configuration files are read from an isolated location. ## Test plan - Existing tests pass - Tests using `with_real_home()` no longer read user config files