fix: accept whitewind entries with visibility "url" (not just "public")
WhiteWind blog entries use three visibility values: "public", "url",
and "author". "url" means publicly accessible via link. Our filter
was dropping everything except "public", which meant every WhiteWind
entry with visibility "url" was silently discarded. Now only "author"
entries are skipped.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>