CLI backends (claude-cli etc) don't emit streaming assistant events,
causing TUI to show "(no output)" despite correct processing. Now emits
assistant event with final text before lifecycle end so server-chat
buffer gets populated for WebSocket clients.
- Add resumeArgs to DEFAULT_CLAUDE_BACKEND for proper --resume flag usage
- Fix gateway not preserving cliSessionIds/claudeCliSessionId in nextEntry
- Add test for CLI session ID preservation in gateway agent handler
- Update docs with new resumeArgs default