feat(workflow): resolve management agent review findings

[reoring]

What

Close out the findings in docs/features/workflow-management-agent-implementation-review.md and add a self-dev loop workflow that can repeatedly implement/test/review until COMPLETE.

Changes

• Isolate management worker events from the main sink/TUI; write management worker events to per-invocation JSONL.
• Unify management directive shape validation across engines and enforce step-state constraints.
• Wire pre_check hook and add check overlays/timeout overrides.
• Resolve management.agent.agent via agent catalog; support step-level per-hook overrides.
• Persist management abort reason in workflow metadata; record engine meta (reasoning/confidence) in decisions log.
• Keep PiSdkEngine read-only (policy/mechanism separation).
• Add variant passthrough for OPENCODE (used to run gpt-5.2 completion reviews with xhigh/high).
• Improve CLAUDE_CODE streaming (use stream-json in STREAM mode, with required flags).
• Add examples/workflow-management-agent-impl-review-loop.yaml + bootstrap script; ignore context/ artifacts.

Verification

• make test-all

Notes

• The PR contains two commits: core implementation + self-dev loop workflow.