feat: the library's folders are set in Admin › Library, and changing a folder moves its tracks with it, keeping their plays, likes and playlists (#6129)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/db/queries/library_settings.sql

@@ -0,0 +1,45 @@
+-- name: GetLibrarySettings :one
+SELECT * FROM library_settings WHERE id = true;
+
+-- name: UpdateLibraryScanPaths :one
+UPDATE library_settings
+   SET scan_paths = sqlc.arg(scan_paths)::text[],
+       updated_at = now()
+ WHERE id = true
+RETURNING *;
+
+-- A library folder that moved (#6129): every path under old_root is rewritten
+-- to the same place under new_root, so the tracks keep their ids and with them
+-- their plays, likes and playlists. updated_at is left alone on purpose: the
+-- scan compares it with each file's mtime, and the files have not changed.
+
+-- name: RerootTrackPaths :execrows
+UPDATE tracks
+   SET file_path = sqlc.arg(new_root)::text || substr(file_path, length(sqlc.arg(old_root)::text) + 1)
+ WHERE starts_with(file_path, sqlc.arg(old_root)::text || '/');
+
+-- name: RerootAlbumCoverPaths :execrows
+UPDATE albums
+   SET cover_art_path = sqlc.arg(new_root)::text || substr(cover_art_path, length(sqlc.arg(old_root)::text) + 1)
+ WHERE starts_with(cover_art_path, sqlc.arg(old_root)::text || '/');
+
+-- name: RerootGrabDestinations :execrows
+UPDATE grabs
+   SET destination = sqlc.arg(new_root)::text || substr(destination, length(sqlc.arg(old_root)::text) + 1)
+ WHERE destination = sqlc.arg(old_root)::text
+    OR starts_with(destination, sqlc.arg(old_root)::text || '/');
+
+-- name: RerootImportRoot :execrows
+UPDATE acquisition_settings
+   SET import_root = sqlc.arg(new_root)::text
+ WHERE import_root = sqlc.arg(old_root)::text;
+
+-- name: SampleTrackPathsUnder :many
+-- A few present tracks under a folder, to check a move before rewriting it.
+SELECT file_path FROM tracks
+ WHERE starts_with(file_path, sqlc.arg(root)::text || '/') AND missing_since IS NULL
+ ORDER BY random()
+ LIMIT sqlc.arg(n)::int;
+
+-- name: CountTracksUnder :one
+SELECT count(*) FROM tracks WHERE starts_with(file_path, sqlc.arg(root)::text || '/');