fix(worker): smooth Qobuz download progress via streamrip byte hook

streamrip reports progress only per concurrent track, so Job.downloadProgress
came solely from the file-count poller — 0% until every track landed, then a
jump to 100%. Patch streamrip.media.track.get_progress_callback to aggregate
per-track byte deltas over an estimated album total (avg started-track size ×
len(album.tracks)) into one smooth, generally-climbing 0..1 fraction routed
through the pipeline's on_progress. Capped at 0.99; the pipeline sets 1.0 on
completion. No signature changes — track count read from the resolved album.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

worker/tests/test_streamrip_progress.py

@@ -0,0 +1,41 @@
+from lyra_worker.adapters._streamrip import _ProgressAggregator
+
+
+def _record():
+    seen: list[float] = []
+    return seen, seen.append
+
+
+def test_equal_size_tracks_aggregate_monotonically_to_near_one():
+    # 4 tracks of 100 bytes each, all started up front (concurrency covers the album), then
+    # each downloaded in 25-byte chunks. Fraction must climb monotonically 0→~1.
+    seen, cb = _record()
+    agg = _ProgressAggregator(4, cb)
+    for _ in range(4):
+        agg.start_track(100)
+    for _ in range(16):  # 16 chunks * 25 bytes = 400 bytes = full album
+        agg.advance(25)
+
+    assert seen == sorted(seen)                 # monotonic non-decreasing
+    assert all(0.0 <= f <= 0.99 for f in seen)  # never negative, capped at 0.99
+    assert seen[-1] == 0.99                      # reaches the cap when all bytes are in
+    assert seen[len(seen) // 2] > 0.3           # genuinely climbs mid-download (no 0→100 jump)
+
+
+def test_estimate_uses_track_count_before_all_tracks_start():
+    # Only the first of 4 tracks has started; with a known track count the estimate already
+    # spans the whole album, so finishing track 1 reports ~1/4, not ~1/1.
+    seen, cb = _record()
+    agg = _ProgressAggregator(4, cb)
+    agg.start_track(100)
+    agg.advance(100)  # track 1 fully downloaded
+    assert abs(seen[-1] - 0.25) < 0.01
+
+
+def test_zero_or_missing_sizes_never_emit_and_never_divide_by_zero():
+    seen, cb = _record()
+    agg = _ProgressAggregator(0, cb)
+    agg.advance(50)          # no track started yet -> no emit
+    agg.start_track(0)       # a track with unknown size
+    agg.advance(50)          # est_total still 0 -> still no emit, no crash
+    assert seen == []