Add local in-memory pubsub

AGENTS.md

@@ -125,11 +125,14 @@ Roadmap items should be actionable and checkable:
   replication and prefix-capability enforcement are still roadmap work.
 - Document resources can be registered locally with empty JSON state and
   local-only status. Automerge editing/state and sync are still roadmap work.
+- Pubsub supports local daemon-lifetime publish/subscribe snapshots through a
+  bounded in-memory ring buffer. Iroh-gossip replication, private topics, and
+  pubsub capability enforcement are still roadmap work.
 - Resource secret epoch metadata can be created, rotated, and listed locally.
   Bearer access metadata can be created/listed/revoked as resource-scoped auth
   ops and must not allow trust graph mutation capabilities. Payload encryption,
   key envelopes, and bearer challenge-response are still roadmap work.
 - Signed peer-card LAN discovery payloads, peer auth over Iroh, cr-sqlite,
-  iroh-docs, iroh-gossip, iroh-blobs, Automerge sync, real auth enforcement,
+  iroh-docs, iroh-blobs, Automerge sync, real auth enforcement,
   OpenSSH KRL generation, and Keyhive/BeeKEM-style authorization are future
   roadmap items unless implemented later.