fix(worker): reject a download with 0-byte/missing tracks (#16 partial)

Completeness only compared the adapter's self-reported track_count to expected,
so a silently-skipped track (0-byte placeholder — see the Qobuz 24K Magic bug)
imported as a "complete" album. Now the verify also counts the NON-EMPTY audio
actually staged and fails "incomplete download" when fewer than expected are
present (guarded with `staged and ...` so fake adapters that stage nothing keep
using the count path). A real broken download now goes needs_attention (or falls
through to another source) instead of importing a dead track.

Full per-track duration matching against MB recording lengths (the rest of #16)
remains a larger follow-up. worker 224 tests / 7-skip.

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

worker/lyra_worker/pipeline.py

@@ -310,7 +310,11 @@ def run_pipeline(
         # 5. verify completeness on the staging copy, then promote + tag
         _set_state(conn, job_id, "tagging", "tag")
         expected = target.track_count if target.track_count is not None else winner.track_count
-        if result.track_count < expected:
+        # Also count the NON-EMPTY audio actually on disk: a silently-skipped track leaves a
+        # 0-byte placeholder that the adapter still counts, so trust the files when any are
+        # staged. (`staged and ...` keeps fake adapters that stage nothing on the count path.)
+        staged = _count_staged_audio(staging)
+        if result.track_count < expected or (staged and staged < expected):
             _fail(conn, job_id, "incomplete download")
             return