Memory & namespaces

type Memory = {
  memoryId: string;       // local id
  namespace: NamespaceId; // "diet" | "health" | "project" | "billing"
  content: string;        // the fact itself
  sourceAgent: AgentId;   // who taught it
  walrusRef: string;      // the REAL Walrus blob id
  createdAt: string;
};

// apps/web/lib/store.ts (simplified)
const { blobId } = await walrus.store(
  { namespace, content, sourceAgent, createdAt },
  MEMORY_EPOCHS,
);
const memory = { memoryId, walrusRef: blobId, namespace, content, sourceAgent, createdAt };