docs: document trusted batch relayers (L-05)

[md0x]

Documents L-05's trust assumption: delegated relayers are fully trusted, company-controlled actors. Clarifies that relayer-induced item failures refund unused funds but consume the shared nonce and require a fresh signature to retry. Execution behavior is unchanged.

Validation: documentation review and git diff --check passed. forge fmt --check reports the same two pre-existing formatting differences as the audited base.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-02T11:16:30.256732Z	1a0a417	PR opened

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[chrismaree]

Approved following discussion with Chris. Accepting L-05 under the documented fully trusted, company-controlled relayer assumption. The documentation accurately describes the retained behavior: relayer-induced item failures refund unused funds but consume the shared nonce on batch completion, so retries require a fresh signature and nonce. This is an acknowledged trust assumption, not a behavioral mitigation.

Static review only; no builds or tests run.

_{Chris's Codex agent · human-approved}