M4: ingestion management (incremental, GS1 supplement, dedup/conflict, quality, scheduler)

- OFF incremental fetch via search API + persistent watermark (ingest_state, migration 0004)
- GS1 barcode supplement adapter (offline mapping + GS1-style API) filling only gaps with field-level provenance
- Non-GTIN dedup with canonical selection + merge_log; field-level conflict resolution (source trust > recency)
- Quality scoring (0.4 completeness + 0.3 source trust + 0.2 multi-source + 0.1 freshness) wired into load/merge
- Jobs: update_off, dedup, schedule; docs/ingestion-management.md
- 19 new tests (pure + DB-integration), ruff clean

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

ingestion/opengoods/jobs/dedup.py

@@ -0,0 +1,40 @@
+"""Deduplicate products: merge non-GTIN duplicates into a canonical record.
+
+Usage:
+    python -m opengoods.jobs.dedup --dry-run
+    python -m opengoods.jobs.dedup --actor nightly
+"""
+
+from __future__ import annotations
+
+import argparse
+import sys
+
+import psycopg
+
+from opengoods.etl.dedup import dedup_all
+from opengoods.etl.load import default_dsn
+
+
+def run(args: argparse.Namespace) -> int:
+    with psycopg.connect(args.dsn, autocommit=False) as conn:
+        summary = dedup_all(conn, actor=args.actor, dry_run=args.dry_run)
+        if args.dry_run:
+            conn.rollback()
+        else:
+            conn.commit()
+    mode = "dry-run" if args.dry_run else "applied"
+    print(f"{mode} groups={summary['groups']} merged={summary['merged']}")
+    return 0
+
+
+def main(argv: list[str] | None = None) -> int:
+    parser = argparse.ArgumentParser(description="Deduplicate OpenGoods products")
+    parser.add_argument("--actor", default="ingestion", help="merge_log actor label")
+    parser.add_argument("--dry-run", action="store_true", help="report only, do not write")
+    parser.add_argument("--dsn", default=default_dsn(), help="PostgreSQL DSN")
+    return run(parser.parse_args(argv))
+
+
+if __name__ == "__main__":
+    sys.exit(main())