Add durable evidence storage and item-level novelty accounting

README.md

@@ -43,3 +43,6 @@ bot/client adapters are future integrations.
 
 Read-only packaged source/database queries and the strict tool allowlist:
 [investigation-tools-v1.md](docs/investigation-tools-v1.md).
+
+Portable evidence records, provenance, case-wide IDs and novelty-aware budget
+integration: [evidence-store-v1.md](docs/evidence-store-v1.md).