Repeated searches and song lookups now reuse a single-flight memory cache, so
concurrent or debounced queries hit YouTube once instead of on every keystroke.
Thumbnails are resolved at a configurable size instead of the largest variant,
which cuts the image payload the browser pulls from Google.
YouTubeMusicService swallowed the exception into an ErrorOr description
with no trace on the server side. Adds ILogger to the three operations.
The download activity no longer names yt-dlp in its messages, since the
downloader is an implementation detail behind IYouTubeDownloaderService.
Track get-or-create for YouTube videos was duplicated between the
old GetYouTubeTrackStream query handler (which also wrote to the
database) and AddYouTubeTrackToPlayList, with frontend-supplied
metadata (title/artist/duration/thumbnail) trusted at add-to-playlist
time instead of resolving it server-side.
Extract YouTubeTrackProvisioner as the single get-or-create path,
resolving structured artist refs (id + name) from YouTube Music so
multi-artist songs map to distinct Artist rows. Rename
GetYouTubeTrackStream to ResolveYouTubeTrackStream (it writes, so it
is a command, not a query) and delegate to the provisioner.
AddYouTubeTrackToPlayList slims down to (UserId, PlayListId, VideoId)
since all metadata now comes from the provisioner/YouTube API.
Playing a YouTube song now creates a lightweight track row (without queueing a download) and writes listening history; saving to a playlist queues the download via the new DownloadRequested flag.