* feat(playback): stream buffering UI, ranged M4A tail prefetch, demuxer fix
Defer seekbar/progress until HTTP stream is armed for both legacy and
RangedHttpSource; show buffering overlay on cover art. Add MP4 tail
prefetch and Symphonia isomp4 bounded-mdat/moov-at-EOF probing so
moov-at-end M4A can start without reading the full mdat.
* feat(hot-cache): spill large ranged streams to disk for promote
When a ranged HTTP download completes above the 64 MiB RAM promote cap,
write the existing buffer once to app-data stream-spill/ and register it
for hot-cache promote (rename) and replay via fetch_data. Analysis seeds
from the spill file up to the local-file cap (512 MiB).
* fix(ui): stream buffering — grayscale cover and static clock icon
Desaturate player and queue cover art while isPlaybackBuffering; keep a
non-animated clock overlay for visibility without the spinning animation.
* fix(playback): review follow-up — tests, i18n, spill cleanup, changelog
Clippy and test layout fixes; stream spill orphan cleanup on startup;
buffering flag guard in progress handler; bufferingStream in all player
locales; CHANGELOG and contributor credits for stream/M4A work.
* docs: attribute stream buffering and M4A streaming to PR #737
* test(audio): avoid create_engine in stream spill unit test
CI runners have no audio output device; test spill take/consume via
the Mutex slot only, matching install_stream_completed_spill tests.
111 of 122 top-level src/utils/ files move into 16 topic folders (audio,
cache, cover, share, server, playback, playlist, deviceSync, waveform,
mix, format, export, changelog, ui, perf, componentHelpers). True
singletons with no cluster stay at the utils/ root.
Pure file-move: a path-aware codemod rewrote 539 relative-import
specifiers across 275 files; no logic touched. The hot-path coverage
gate list (.github/frontend-hot-path-files.txt) is updated to the new
paths for the 11 gated utils files — a mechanical consequence of the
move, not a CI change. tsc is green.
cucadmuh
Frank Stellmacher