dispatch() only converted reply-wait timeouts into AgentTimeoutException.
A lazy-connect TCP/TLS failure (raw ETIMEDOUT etc.) threw an uncaught
transport exception instead, bypassing the graceful 504 handling callers
already rely on. Now the whole subscribe/publish/poll sequence is
wrapped, the broken client is discarded, and any transport failure is
rethrown as AgentTimeoutException.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>