feat: v0.3.0 — State, Memory, message_status, MCP instructions

Phase B + C + message delivery status.

State: shared key-value store per mesh. set_state pushes changes
to all peers. get_state/list_state for reads. Peers coordinate
through shared facts instead of messages.

Memory: persistent knowledge with full-text search (tsvector).
remember/recall/forget. New peers recall context from past sessions.

message_status: check delivery status with per-recipient detail
(delivered/held/disconnected).

Multicast fix: broadcast and @group messages now push directly to
all connected peers instead of racing through queue drain.

MCP instructions: dynamic identity injection (name, groups, role),
comprehensive tool reference, group coordination guide.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/db/migrations/meta/_journal.json

@@ -57,6 +57,13 @@
       "when": 1775476994511,
       "tag": "0007_add-presence-groups",
       "breakpoints": true
+    },
+    {
+      "idx": 8,
+      "version": "7",
+      "when": 1775477883426,
+      "tag": "0008_add-state-and-memory",
+      "breakpoints": true
     }
   ]
 }