When an extension queues a follow-up during `agent_end` it
gets stuck on the follow-up queue until after the next user
message.
Add a hasQueuedMessages() check to _handlePostAgentRun
so the existing while/continue loop drains them.
- One-line fix in _handlePostAgentRun
- Integration test in agent-session-queue
- git-merge-and-resolve example extension with tests
Danny Thomas