perf: streamline spec-superflow execution and test runtime

[MageByte-Zero]

Summary

• add risk-adaptive lightweight execution with explicit escalation to Full
• remove repeated command and Git validation work while retaining independent risk coverage
• standardize phase handoffs and archive verified workflow evidence

Verification

• npm run build
• npm test — 653 passed, 0 failed, 164.38s (under the 180s reference target)
• focused hotspot suite timing and review receipts recorded in the change artifacts