feat: recommend execution modes at DP-4

[MageByte-Zero]

Summary

• add evidence-based Inline, Batch Inline, and SDD recommendations for DP-4
• require a current recommendation receipt plus explicit confirmation for plans and revisions
• keep recommendation receipts tied to artifacts, contracts, waves, and the immediately prior plan revision
• update skills, installers, docs, and coverage across execution guards

Verification

• npm run build
• npm test (397 passing)
• npm run validate -- docs/examples/add-dark-mode
• npm run validate -- docs/examples/refactor-auth-boundary
• node scripts/spec-superflow.mjs doctor
• npm pack --dry-run --json