The CLIP encode failure reason was only ever returned in the HTTP response
body, never logged server-side, making 502s from /photos/search opaque. Log
the underlying cause — network error to the URL, or the Apollo HTTP status +
response body — so CLIP-service problems are diagnosable from the ImageApi log.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>