Add OCR fallback via Ollama Vision for albums without tracklist text

hint_extractor: _ocr_back_cover() sends back/inlay images to Ollama Vision
  when no tracklist .txt/.htm/.nfo is present. Model priority:
  qwen3-vl:latest → minicpm-v:latest → deepseek-ocr:latest (configurable
  via OLLAMA_OCR_MODEL env var). Timeout 180s. OCR text is fed into the
  same _parse_tracklist() pipeline as regular text files.

music_enricher: extract_hints(use_ocr=not args.no_api) — OCR is skipped
  with --no-api to allow fully offline/fast runs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

music_enricher.py

@@ -90,7 +90,7 @@ def process_album(
             stats["skipped"] += 1
             return stats
 
-        hints = extract_hints(scan)
+        hints = extract_hints(scan, use_ocr=not args.no_api)
 
         proposal = resolve(
             hints,