docs(governance): per-loop promotion-criteria pages (evidence thresholds per the ADR schema)

[williamzujkowski]

Part of #3839. Depends on #3840, #3843.

Context

Each ladder-resident loop gets a short promotion-criteria section: what evidence (per the ADR schema), measured where, threshold, and the demotion triggers. The two with live measurement surfaces anchor it: #3769 (would-block rate via #3727) and #3815 (getResearchMaturityReport lift). pr_review's criterion is owned by Epic E — link, don't duplicate.

Acceptance criteria

• Criteria pages/sections for: tune loop (what would DEMOTE it), auto-remediation (feat(capability-loop): flip auto-remediation default to audit (then enforce when readiness passes) — sequenced #3769's threshold restated per schema), KNN weighting (feat(routing): weight KNN routing by research-maturity — GATED on measured success-rate lift (#3234 follow-up) #3815), learned selection (MetaOrchestrator step 4: enforce learned selection once it beats rules #3552), ClawGuard (feat(security): consider flipping ClawGuard default from audit to enforce after bake period #2077)
• Each criterion entered in the claims registry as an aspirational→verified transition path
• Indexed in docs/README.md

Evidence required

Docs gates; claims registry entries.

Out of scope

pr_review criterion (Epic E).