CHW-4609 CachePathInvalid

cache purge path is malformed; expected /api/cache/repos/{repo}/packages/{package}/{version}

Default message: cache purge path is malformed; expected /api/cache/repos/{repo}/packages/{package}/{version}
HTTP status: 400 (client)

Problem. The cache purge URL did not parse. Cause. The expected shape is /api/cache/repos/{repo}/packages/{package}/{version}; the request was missing the /packages/ segment, the trailing version, or one of the required path components. Fix. Construct the URL with all three segments and resubmit. HTTP 400.