c7be324083
Cherry-pick of KeygraphHQ/shannon#295 (581c208). Upstream changes: removes router mode from CLI/worker, adds provider extensions, new report-output-provider and checkpoint-provider interfaces, refactored workflow orchestration. Conflicts resolved: kept our README.md, CLAUDE.md, and deleted compose files. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>