v0.5.2 — One source of truth for the plumbing

🧱 De-duplication

Removed three sets of copy-pasted logic a reviewer would rightly flag:

• Claude CLI wrapper (was in 3 files) → lib/claude-cli.ts
• LLM-JSON extraction (3 near-identical parsers) → lib/llm-json.ts extractJson()
• child_process spawn/capture (git + crew) → lib/exec.ts capture()

No behavior change. Type-check + build green, crew dry-run 7/7.