feat(risk): expand risk anchors + known-address registry

[spalen0]

Summary

Two small, independent improvements to the AI explainer's risk grounding. Branched off main so it's reviewable independently of #243.

Expanded risk anchors (utils/risk_anchors.py)

Anchors stabilize the LLM's risk verdicts by giving well-understood selectors a typical floor/ceiling. Added the ones most relevant to Safe monitoring — they change who or what can move multisig funds:

Selector	Anchor
enableModule(address)	CRITICAL — a module can move funds with no owner signatures
addOwnerWithThreshold / removeOwner / swapOwner	HIGH — Safe signer set changes
changeThreshold(uint256)	HIGH — signatures-required change
setGuard(address)	HIGH — a guard can permit/block every Safe tx
disableModule / setFallbackHandler	MEDIUM
acceptOwnership()	HIGH — completes an Ownable2Step handover
mint(address,uint256)	MEDIUM — new supply, elevate if large/unbacked

A test recomputes each selector from its signature to guard against typos, and validates the whole table (well-formed keys, valid levels).

Known-address registry (utils/known_addresses.py)

A curated address → label map wired as the highest-priority resolver backend, ahead of Etherscan/swiss-knife. A correct label lets the LLM reason about who an address is — grantRole to a known multisig reads very differently from grantRole to an unknown EOA.

• Seeded only with canonical burn/null addresses (a transfer to 0x…dEaD is a burn — universally correct, useful signal).
• _BY_CHAIN is left empty for per-deployment curation — I did not fabricate multisig addresses. Populate with verified Yearn multisigs/EOAs (there's a commented example).

Deferred (need #243 or your input)

• Bundle simulation for state-dependent batches — entangled with feat(llm): safety checks, intent comparison, system-prompt caching, sim overrides #243's simulation.py changes; better as a follow-up once that merges.
• Refine-cost audit — overlaps the prompt tuning under review in feat(llm): safety checks, intent comparison, system-prompt caching, sim overrides #243.
• Populating the registry — needs your verified address list.

Testing

367 passing, lint clean, no new mypy errors.

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