docs: summarize ADR deferral convergence

[verlyn13]

Purpose

Add two generated, derived, non-authoritative views under ADR 0081 without changing successor extraction:

• a file-addressable successor table over canonical ADR numbers and admitted repository paths, counting unique deferring ADRs;
• a review-only exact-token gateway rollup with unique ADRs and source-span links, but no successor identity, existence state, or edge claim.

This is a follow-on stacked on #104. Its base is feat/adr-deferral-index, so this PR contains only the rendering amendment.

Ring changed

• Ontology/schema
• Kernel
• Adapter
• Dashboard
• Hook
• Eval
• Docs

Boundary checks

• No policy duplicated into adapter/hook
• No universal shell execution added
• No audit-write agent endpoint added
• OperationShape remains upstream of CommandShape
• Evidence includes provenance/freshness where applicable
• Dashboard impact considered
• Citation discipline — ADR 0081 §Decision authorizes the generated index and states: “Choose Option A. Add a dependency-free generator”; D-089 records this follow-on as rendering-only. No out-of-scope text is used as implementation authorization.
• Precedence respected — ADR 0081 remains the governing decision; this PR changes no lower-precedence rule to evade it.
• Charter text quoted verbatim or untouched — charter text is untouched.

Validation

just verify
  ✓ node-tools
  ✓ static-gates
  ✓ fixtures
✓ all quality gates passed

No scoped package test applies; the generator's embedded fixtures run in adr-deferral-index-check through just verify.

Charter compliance

Complies with implementation charter v1.6.0. Ring: documentation/Class J; no runtime ring or cross-ring import changes.

Agent use

• Implementer: Codex, Class-J documentation generator
• Reviewer: hcs-architect
• Subagents: hcs-architect; two read-only implementation explorers