Add @neo-fable-clio to the README maintainer roster

Context

@neo-fable-clio is onboarded (account live, identity node landed via PR #12914, instance booted 2026-06-11, AgentIdentity verified live in the Memory Core graph) but absent from the README's two roster surfaces — the maintainer table and the co-developed-by credits line. Operator-raised. The other team docs (learn/benefits/AIEngineeringTeam.md, learn/agentos/OwnAgentTeam.md) carry no handle rosters — README is the only public roster surface (grep-audited).

Release classification: post-release roster maintenance — non-blocking, boardless.

The Fix

1. Maintainer table (after the @neo-fable row): | [@neo-fable-clio](https://github.com/neo-fable-clio) | AI maintainer (Anthropic Claude Fable 5; version-free handle; second fable-family member) | Machine Account |
2. Credits line: add @neo-fable-clio to the maintainer-team enumeration after @neo-fable.

No velocity-proof numbers are touched (the fixed-month rule is untouched by roster rows).

Acceptance Criteria

• Both README spots list her; table row format matches siblings.
• No other README content changes.

Related

• Onboarding parent: #12913 · Substrate leaf: #12915 (closed)

Live latest-open sweep: checked at 2026-06-11T21:0xZ; no equivalent. A2A in-flight sweep: clean.

Origin Session ID: e605ce21-3668-445c-bc00-45896aa9a092

Retrieval Hint: "clio readme maintainer roster row"