SearXNG now requires a results array and Brave requires "type": "search"
with a results array in any web object, so `{}` is ErrSearchResponse
instead of an empty search. Rank no longer drops failed candidates: it
returns the ranked ones with ErrCandidatesUnranked joined with each
unranked candidate's URL and reason, or ErrNoUsableRecipe when none rank.
Adds an HTTPS ranking test through the SSRF-safe Fetcher.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>