Moves the remaining uncommitted work: the home gets quick mixes and a
"Tus álbumes" shelf, saving a YouTube album now goes through
addYoutubeAlbumToPlaylistAction instead of the SaveYouTubeAlbum command,
and UserAlbum drops its unused ExternalId.
The mixes section keeps its current shape (no refresh action, no badge,
hidden when empty) rather than the older version the worktree carried.
The albums section keeps a Ver más button while YouTube Music has another
page, fed by a new /api/youtube/albums route that forwards the continuation
token. The YouTube album page gains a save button that drops the whole album,
tracks included, into your library and takes you to it.
The browser used to pull every cover straight from Google, so a search grid
plus infinite scroll fired dozens of cross-origin image requests and started
coming back as 429. Covers now go through /api/youtube/thumbnail, which
resizes the upstream URL, caches the bytes in memory, collapses duplicate
in-flight fetches, caps the concurrency against Google and backs off when it
answers 429. Responses are immutable for a month and revalidate with an ETag,
and serving them same-origin also lets the accent extractor read the pixels.
Updates the compose build context, the Dockerfile header, the package
name and the docs. The compose service and container keep the name
frontend/musify-frontend, since nginx routes to http://frontend:3000.
The source files also carry the first prettier pass, so the rename and
the reformat land together for them.