Add US Code CID BM25 and KG artifacts

Rebuild clean U.S. Code retrieval artifacts: lean CID index, BM25 over section text/citation/title metadata with raw_json excluded, and generic legal-document knowledge graph entities/relationships/summary.

uscode_parquet/cid_index.parquet

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:608b1e3742ee2fab0eda29cb05209e84840052d8bee3b2f8de18e72611fa89e4
-size 3575375
+oid sha256:820c24c37107efeacee2f1014a87ec5312d64ce103b790c138bdbb914a477ac1
+size 6112895

uscode_parquet/laws_bm25.parquet

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:0cdcb3227c1571c16790986952dd914e0ff208dabeeb61f8e2fa1de422f279cf
+size 199566685

uscode_parquet/laws_knowledge_graph_entities.parquet

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:77aa4e3f71d88c157d9856a02cd5bb5cd03d52307873e2a03fd9216c67e0ce83
+size 9653603

uscode_parquet/laws_knowledge_graph_relationships.parquet

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:746f9b81669c26c93ae418e2ca1b560738f4aa93a140a13d1a0390bffac080fb
+size 10805567

uscode_parquet/laws_knowledge_graph_summary.json

@@ -0,0 +1,23 @@
+{
+  "bm25_document_count": 60068,
+  "cid_index_row_count": 60068,
+  "document_count": 60068,
+  "entity_count": 180257,
+  "entity_type_counts": {
+    "document": 60068,
+    "legal_document": 60068,
+    "section": 60068,
+    "usc_title": 53
+  },
+  "note": "BM25 built from section text plus citation/title metadata only; raw_json intentionally excluded.",
+  "ontology": {},
+  "ontology_version": "generic-legal-document-kg-v1",
+  "relationship_count": 120136,
+  "relationship_type_counts": {
+    "HAS_SECTION": 60068,
+    "IN_TITLE": 60068
+  },
+  "schema_version": "uscode-kg-v1",
+  "source_dataset": "justicedao/ipfs_uscode",
+  "source_rows": 60077
+}