fix: cookbook tree runner stdout/stderr separation and bash brace expansion
- Fix bash brace expansion issue with ${2:-{}} defaults causing extra } chars
- Redirect step status messages to stderr to prevent JSON output pollution
- Redirect wait_pipeline/wait_site/diagnose output to stderr
- Add SDLC handler tests for state, features, tasks, artifacts endpoints
- Add SDLC classifier tests for phase transitions and blocking
- Add SDLC CLI command tests for feature, task, branch, merge operations
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
6c51469c89