`<d:href>` is required by RFC 3986 to be percent-encoded, so non-ASCII
filenames (e.g. Chinese, Cyrillic) were leaking through `list_directory`
and the SEARCH-based tools (`find_by_name`, `find_by_type`,
`list_favorites`, `search_files`) as their URL-encoded form. Decode with
the already-imported `urllib.parse.unquote` before exposing to callers.
Fixes#776
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>