Update card: sharded per-incident GraphML layout

README.md

@@ -209,7 +209,7 @@ Complete incident records as produced by WitFoo Precinct's threat detection engi
 
 - **`graph/graph.graphml`** — Full provenance graph in GraphML format (streaming write; ~477 MB)
 - **`graph/graph.json`** — NetworkX node-link JSON format
-- **`graph/incidents_graphml/{incident_id}.graphml`** — 13,119 per-incident GraphML files (~1 MB total). Each is small and loadable in Gephi, NetworkX, igraph, or DGL. Useful for graph-based research where loading the entire dataset is impractical.
+- **`graph/incidents_graphml/{0-f}/{incident_id}.graphml`** — 13,119 per-incident GraphML files, sharded into 16 subdirectories by first hex char of the incident UUID (HuggingFace caps directories at 10,000 files). Each file is small (KB-MB) and loadable in Gephi, NetworkX, igraph, or DGL. Useful for graph-based research where loading the entire dataset is impractical. Total ~143 MB.
 - **`graph/attack_reports.jsonl`** — Natural-language threat-hunting reports, one per incident. See [Attack Reports](#attack-reports).
 - **`reference/lead_rules_catalog.json`** — Complete catalog of 261 WitFoo lead detection rules, 158 security products, 106 classification sets, and 216 stream-to-product mappings