docs: ship in-house RN checkout, scope 5 follow-up tasks (#7-11)

In-house Request Network checkout went fully end-to-end on dev today.
A real 0.01 USDC payment flowed through wallet connect -> approve ->
ERC20FeeProxy.transferFromWithReferenceAndFee -> RN webhook ->
TransactionSafetyProvider -> Payment.status=completed -> page success
state. Tx 0x494c77a29161b5100d8e0b1ac675f1822955d0bb3633ecdbfafb886f84f2f320.

Docs:
- New PRD: Wallet, Multichain, Confirmations, AML, Trezor
  (5 follow-ups, each sized for an independent contributor)
- Updated PRD: Request Network In-House Checkout (phases 0..3 done,
  phase 4 partial, phases 5-6 not started)
- Updated handoff: deployed versions, what is working end-to-end,
  follow-up tasks index

Taskmaster: 5 new top-level tasks (#7..#11) covering ephemeral
destination wallets, multichain proxy registry + USDC/USDT, runtime
confirmation thresholds, optional seller-paid AML screening, and
Trezor signing for admin actions. Tasks are scoped fine-grained so
each is independent enough for kimi to pick up.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Taskmaster/Tasks/task-10.md

@@ -0,0 +1,35 @@
+---
+taskmaster_id: "10"
+status: "pending"
+priority: "medium"
+depends_on: []
+parent_id: ""
+source: "taskmaster"
+generated_at: "2026-05-28T11:49:27.076Z"
+---
+
+# 10 - Optional AML screening on incoming payments (seller-paid)
+
+- [ ] 10 - Optional AML screening on incoming payments (seller-paid) #taskmaster #priority/medium #status/pending 🔼 🆔 tm-10
+
+## Metadata
+
+| Field | Value |
+| --- | --- |
+| Taskmaster ID | 10 |
+| Status | pending |
+| Priority | medium |
+| Dependencies | None |
+| Parent | None |
+
+## Description
+
+Turn the existing aml_screening placeholder in TransactionSafetyProvider into a real Chainalysis (or equivalent) Address Screening call that the seller opts into per-offer and pays the per-check cost for.
+
+## Details
+
+See PRD - Wallet, Multichain, Confirmations, AML, Trezor.md §4. Default provider recommendation: Chainalysis Address Screening (cheapest, simplest). Files: new backend/src/services/payment/safety/amlProvider.ts interface + chainalysisProvider.ts impl behind env TRANSACTION_SAFETY_AML_PROVIDER=chainalysis with API_KEY in KMS; transactionSafetyProvider's evaluateAmlPlaceholder() becomes real, persists raw provider response on Payment.metadata.amlResult; Offer schema add requireAmlCheck + amlBlockOnFailure booleans; offer-edit UI toggle 'Require AML on incoming payments ($X per payment, paid by you)'; admin global config UI for provider selection + API key rotation + per-chain enabled flag; cost accounting: deduct per-check cost from seller's escrow on completion as a separate ledger line item, surfaced on payment-details. Open questions before code: pick provider (Chainalysis vs TRM vs Elliptic — need 1-page comparison of cost/latency/coverage); failure mode (fail-closed only when seller opted in AND amlBlockOnFailure=true, else warn/log); cost batching cadence. Acceptance: seller toggles AML on an offer; incoming payment triggers a real Chainalysis call; sanctions verdict blocks the safety gate; clean verdict passes; seller's settled amount reduced by check cost; admin can rotate API key without redeploy; provider-down + amlBlockOnFailure=true keeps payment pending with provider_unavailable reason. Dependencies: none. This is task #10 in the PRD.
+
+## Verification
+
+_No verification strategy._