Auto-review follow-ups for PR #222: feat(protocol)!: bind the ephemeral key into the ready signature

[github-actions]

Tracking auto-review follow-ups for #222 (verdict: warn).

🟡 Nits

• Six integration test files (mutual-auth-idb, graphql-query, read-cookies, all-bootstrap-verbs, two-mcps, reconnect) left concatBytes imported but unused after switching sig-payload construction to readySignaturePayload(...)

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When addressing the review on #222, resolve each item and add Closes #<this issue> to the PR once everything is genuinely fixed; deferred items stay open here. See the auto-review follow-up convention in CLAUDE.md.