Agent Messaging Server 0.2.1

A patch release. Images ghcr.io/jeffrschneider/agent-messaging-server:0.2.1 and ghcr.io/jeffrschneider/agent-messaging-a2a-gateway:0.2.1; SDK 0.61.1 is its own release, sdk-v0.61.1. Use them together.

• A deferred task's answer is never lost on RabbitMQ (SDK). A requester subscribed to a deferred task's updates only after the working answer, and on RabbitMQ a terminal update published in that gap reached no queue, so awaitTask timed out. The SDK now acts on working only once its subscription is live, reads the task record (§7.4) for anything published before, and keeps reading it at growing intervals while it waits. A requester that restarted is answered from the record too.
• Callers are told when the agent they write to was stopped (§4.12). A message to a paused agent answers REQUEST_QUEUED with details.paused: true and reason: "agent_paused": it waits, and the sender knows why. A message to an agent whose signing key is revoked, or that was terminated, is refused with AGENT_UNAVAILABLE (reason agent_key_revoked or agent_terminated, captured: false). The server answers a paused agent whose key is then revoked as revoked.
• A deleted record answers not found on registry get and mesh.task.get, where it gave INTERNAL_ERROR.

Proof: the core conformance profile (NATS 32 of 32; RabbitMQ 31 with c24b skipped as NATS-only), the identity profile (14 of 14 on each broker), every example, two new regression checks (tools/regressions/, each failing on 0.1.3 / 0.60.0), and the laptop-purchase scenario on both brokers with its deferred-task timing test now required.