Add @neo-opus-grace to README maintainer institution surfaces

Context

PR #12415 (Resolves #12413) activates the @neo-opus-grace AI maintainer identity in the graph roster (ai/graph/identityRoots.mjs) — the second Anthropic Claude-family maintainer, sibling of @neo-opus-ada. The human-facing identity surface in README.md was not updated in the same PR, so once #12415 merges the graph roster and the README are out of sync: the README still lists only four maintainers and omits the newly-activated peer.

The Problem

README.md is the canonical human-facing roster of the maintainer institution. Two spots enumerate the maintainers, and both omit @neo-opus-grace:

• The "Institution Inside the Brain" table (~lines 73-78): rows for @tobiu, @neo-opus-ada, @neo-gemini-pro, @neo-gpt.
• The Contributing paragraph (~line 194): "...the AI maintainer team (@neo-opus-ada, @neo-gemini-pro, @neo-gpt)...".

Leaving this drifted means the public identity surface understates the swarm and contradicts the activated graph roster — exactly the multi-surface identity-coherence problem the neo-identity-update skill (ADR 0018) exists to prevent.

The Architectural Reality

• Canonical roster: ai/graph/identityRoots.mjs (AgentIdentity root nodes) — post-#12415 includes @neo-opus-grace (active).
• @neo-opus-grace is same-family (modelFamily: 'claude', siblingOf: '@neo-opus-ada'). Its role is same-family throughput + same-family review pressure; per identityRoots.mjs it does NOT satisfy cross-family approval for Claude-authored PRs. The README's "rival labs — Claude, Gemini, GPT" framing therefore stays correct (still three labs; two Claude identities).
• Agent-facing surfaces already carry the identity: learn/agentos/ModelStats.md (pending row) + learn/agentos/Tier2RevalidationSweep.md. A rg sweep confirms README.md is currently the only human-facing surface that enumerates the @neo-* roster (VISION/STORY/package.json/learn-benefits do not).

The Fix

Apply via the neo-identity-update skill (multi-surface identity coherence):

• Add a @neo-opus-grace row to the README institution table with an accurate same-family role description (e.g. "AI maintainer (Anthropic Claude — same-family generalist; throughput + same-family review pressure)"), linked to https://github.com/neo-opus-grace.
• Add @neo-opus-grace to the Contributing paragraph maintainer list.
• Do not alter the "rival labs — Claude, Gemini, GPT" cross-family framing.

Acceptance Criteria

• README institution table includes a @neo-opus-grace row with same-family role description + correct GitHub profile link.
• README Contributing paragraph lists @neo-opus-grace.
• Role text does not imply a fourth rival lab and does not claim cross-family review authority for the same-family sibling.
• neo-identity-update skill consulted; any other roster-bearing surface it enumerates is checked (current sweep: README is the only human-facing roster surface).

Out of Scope

• learn/agentos/ModelStats.md pending→active row flip (track via #12415 scope or separately — see Related).
• Any change to cross-family quorum / review-authority semantics.
• Activating further identities.

Decision Record impact

aligned-with ADR 0018 (Neo identity facts-vs-framing; neo-identity-update skill foundation). No ADR challenge/supersede.

Related

• Follows: #12415 (activates the identity — README sync should land after it merges), #12413 (activation ticket).
• Adjacent surface: learn/agentos/ModelStats.md pending row → verify active flip.

Origin Session ID: 4cfb33e9-9d3a-4af7-afa8-e3d71ed4bcc7 Retrieval Hint: "neo-opus-grace README institution table identity surface sync #12415"