feat(decision-council): trace proposals to approved outcomes

[9uiLe]

Summary

• freeze owner-approved, versioned Outcome Register entries before deliberation
• assign source-namespaced Proposal IDs and trace every material proposal/concern to active Outcome IDs
• audit challenge link changes and require one evidence → proposal → outcome trace per accepted proposal
• detect untraced proposals, means-as-goal drift, unauthorized outcome changes, hidden tradeoffs, and confidence increases without new outcome evidence
• keep a guard-complete COMPACT mode for low-stakes decisions
• add a deterministic record validator and behavioral fixtures for all Issue [Decision Council] Trace every proposal to frozen outcomes and detect means-goal substitution #55 scenarios

Dogfooding

Decision Council was used during implementation with frozen outcomes O1–O3, independent Fable/Codex round-one reviews, and an anonymized challenge. The council identified missing confidence-drift detection, ID/version ambiguity, proposal collisions, tradeoff authorization, link history, compact semantics, and weak lexical tests. Those findings were dispositioned and implemented before final review.

Verification

• node --test plugins/second-opinion/tests/decision-council-contract.test.mjs
• node --test plugins/second-opinion/tests/*.test.mjs
• skill validation
• plugin validation
• scripts/verify-versions.sh
• git diff --check
• independent Standards review: pass
• independent Issue [Decision Council] Trace every proposal to frozen outcomes and detect means-goal substitution #55 Spec review: pass

Closes #55