docs(operations): LLM usage-attribution research catalog

Deep-research reference for per-consumer tracking of the fleet endpoints:
measured baseline (no identity anywhere; frank-zealot /metrics 501), the
seven identity layers, engine-native/gateway/tracing/network catalogs with
citations, and a phased adoption plan.

serverAppConfigs-docs/index.md

@@ -134,6 +134,9 @@ skill-cluster. See [log.md](log.md) for the wave plan and results.
   posture, whole-fleet audit, bulk redaction
 - [[SSH and Remote Access]] — passwordless bootstrap, fish login shells,
   GUI-hang diagnosis over ssh
+- [[LLM Usage Attribution]] — who-is-using-the-fleet-LLMs research catalog:
+  engine-native identity, gateways, tracing, network/host attribution,
+  phased plan
 
 **Architecture:**