Auto-merge: when ingest pipeline detects "source file missing", now checks
if the track already exists in the library by file_hash. If so, marks the
pending entry as 'merged' instead of 'error' — avoiding stale error entries
for files that were already successfully ingested in a previous run.
Prompts: replaced Pink Floyd/The Wall/Have a Cigar examples in both
normalize.txt and merge.txt with Deep Purple examples. The LLM was using
these famous artist/album/track names as fallback output when raw metadata
was empty or ambiguous, causing hallucinated metadata like
"artist: Pink Floyd, title: Have a Cigar" for completely unrelated tracks.
Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>
