fix(windows): resolve Claude config without environment home

[insane66613]

Summary

• add a Windows profile-directory fallback for environments where Path.home() cannot resolve
• use the Windows shell profile path before constructing AppData\Roaming and AppData\Local fallbacks
• preserve the existing environment-variable and Path.home() behavior when those sources are available

Problem

_claude_desktop_candidate_paths() currently calls Path.home() after APPDATA / LOCALAPPDATA are absent. On Windows, clearing the environment can make Path.home() raise RuntimeError: Could not determine home directory, including in the existing test_windows_path_falls_back_when_appdata_is_missing case.

Implementation

The fallback order is:

1. Path.home()
2. SHGetFolderPathW(CSIDL_PROFILE)
3. SYSTEMDRIVE\Users\<os.getlogin()>

The helper raises the original Path.home() error when no reliable Windows profile path can be resolved.

Validation

• uv run ruff check .
• uv run ruff format --check .
• uv run pytest tests/cli/test_setup_claude_desktop.py -q — 39 passed
• full upstream-first integration stack on Windows — 1,318 passed, 39 skipped

Manual Windows reproduction: with home-related environment variables cleared, Claude Desktop config-path resolution returns a profile-based path instead of raising from Path.home().

No new dependencies.