feat(action-provider): add Agenda pre-sign evidence review

[vassiliylakhonin]

Summary

Adds an optional AgendaGuardActionProvider for reviewing caller-supplied EVM transaction evidence. This is an explicit AgentKit action, not automatic interception of other wallet actions.

Review boundary

• Every returned result has is_safe: false: either reject or step_up_human_required.
• Legacy local risk-denylist matches, unlimited approval patterns and suspicious intent can reject a proposal. The denylist is not a current authoritative sanctions dataset.
• Single-transaction and optional daily-history comparisons use caller-reported values, not an authoritative wallet ledger. Missing history is not replaced with zero.
• HTTP failures, HTTP 402, malformed responses and remote allow never authorize signing or broadcasting. A remote rejection can tighten the result.
• Finite, nonnegative amounts/history and finite, positive configuration limits are validated.
• EVM network support only; endpoint=None provides local review without sending evidence to the remote service. The default remote endpoint receives the supplied transaction evidence; redirects are disabled.
• No signing, transaction execution, payment proofs, automatic paid retries or escrow payouts are implemented.

Verification

• Provider regression suite: 43 passed, all provider HTTP calls and SDK analytics mocked.
• Python package unit suite: 712 passed, 35 e2e/integration tests deselected.
• Whole-package Ruff lint and formatting checks: passed.
• git diff --check: passed.
• Registered action description: 548 characters (checked directly). The existing check-description-length entry point cannot run in this upstream checkout because its referenced scripts module is absent.
• Independent read-only candidate review found no surviving authorization bypass or concrete regression.
• No funded transactions or live paid evaluations were performed.

Includes a changelog fragment and updated usage/privacy/payment documentation. The original unsigned contribution was replaced by a single GitHub-verified signed commit to follow CONTRIBUTING.md. Maintainer review is still required.

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1

[vassiliylakhonin]

Updated this existing PR after reviewing its authorization boundary. The action now always returns is_safe: false, with either rejection or mandatory human review; HTTP errors, payment-required responses and remote allowances cannot authorize signing. Caller-reported history is no longer fabricated as zero. Added finite-number validation, offline mode, EVM scoping, a changelog and accurate documentation.

Verification: 43 mocked provider regression tests and 712 package unit tests passed; package Ruff lint/format checks passed. No live paid evaluations or funded transfers were performed. The legacy description-length entry point references a missing upstream scripts module; the registered action description was checked directly (548 characters).

The contribution is now one GitHub-verified signed commit, replacing the initial unsigned commit. Ready for maintainer review; this remains an optional evidence-review action, not automatic wallet enforcement.