Local tracks now show embedded title/artist/album art (via native
MediaMetadataRetriever, cached through the existing FileProvider)
instead of the raw filename, falling back gracefully when a file
has no usable tags. Adds two navigable entry points per folder: sort
by audio quality (bitrate, capped at 150 tracks per folder to bound
worst-case latency) and alphabetical name buckets -- the closest
realistic form of "filtering" given Android Auto has no text-search
UI in this integration.
Metadata resolves only for the page actually being browsed (same
slice-cheap-then-map discipline as the paging change), backed by a
flat 256-entry LRU session cache that survives across pages. No new
permission, no new pub dependency, no l10n changes (car-tree labels
stay hardcoded Spanish, matching every existing label in the tree).