- resolve_adapter: identify from the yt-dlp extractor_key only, not the full
webpage_url (a sibling source's name in a URL path no longer misresolves);
add youtube-nocookie.com to the YouTube host match so nocookie embeds keep
the POT/player-client extraction strategy.
- _download: re-resolve the adapter with the post-extraction info dict so the
.nfo uniqueid type and uploader_url agree on one source (dedups the inline
resolve too).
- MediaMeta.uniqueid_type defaults to source-neutral "generic" instead of
"youtube", so an un-updated caller can never falsely label a non-YouTube
download as youtube.
- Tests: lock extractor-key-only resolution + nocookie host; default nfo type.