_try_staging_match() built a minimal context missing spotify_artist,
spotify_album, is_album_download, and has_clean_spotify_data. Post-
processing returned early at the missing-spotify_artist guard and the
copied file was left at the transfer root with its original filename.
Now mirrors the sync modal worker's context-building: uses
_explicit_album_context/_explicit_artist_context when available
(artist-page album downloads), falls back to track.album/track.artists
for playlists and sync modal. track_number and disc_number are also
forwarded so multi-disc albums land in the correct Disc N/ subfolder.
61c6b6f3f9
