The UserIdleHandler injected its "are you still there?" and disconnect
prompts as role="user" messages. These are agent-side directives, not
user utterances, so they should be injected as role="system" to avoid
polluting the conversation transcript with fake user turns and to read
correctly by the LLM. Updated the realtime append tests to match.
Also forward ports 3000 (UI) and 8000 (API) in the devcontainer so the
running services are reachable from the host.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
