Ingest Marks Batch

Idempotent chunked-ingest endpoint. See services/bulk_ingest.py for design.

Body (JSON): { "kind": "uspto" | "euipo" | "wipo" | "test", "run_id": str, # unique per backfill session "batch_number": int, # 0-indexed monotonic within run "rows": [ {marks row}, ... ] }

Response (JSON): { "ok": true, "batch_hash": "sha256hex", "rows_seen": int, "rows_committed": int, "skipped_duplicate_batch": bool, "committed_at": "iso8601" | null }

Idempotency: same (kind, batch_number, first serial, last serial, row count) produces the same batch_hash. Duplicate submissions are no-ops that return skipped_duplicate_batch=true.