v0.8.4

What's Changed

• feat(agents): add read-only impact-reviewer subagent for audit consolidation checks

The loop auditor now launches an impact-reviewer subagent during section and final audits to scan the scoped change set for duplication of existing helpers, parallel implementations, missed callers of changed shared code, and dead code. It is read-only (no edit, write, review-write, plan-adjust, or task tools), hidden from the agent picker, and returns a text report of blocking/advisory findings that the auditor verifies before writing them as review findings.