v0.1.5

Added

• Agent-to-agent messaging over MCP. A new emit_agent_message tool sends a
  message to a named agent (or * for everyone), and the recipient reads it
  with the cursor-paginated read_agent_messages tool. A waitbus://agent/{name}
  resource acts as a doorbell that pings when a message arrives, so the agent
  reads only when there is something to read. Messages share the event store but
  stay out of the default tail_events and waitbus://current views; tail_events
  gains an event_types filter so a client can opt into them. Agent identities are
  cooperative and self-asserted — the bus is single-user and same-UID, so this is
  not a security boundary.