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-6.md

@@ -0,0 +1,35 @@
+---
+taskmaster_id: "6"
+status: "done"
+priority: "high"
+depends_on: []
+parent_id: ""
+source: "taskmaster"
+generated_at: "2026-05-28T11:49:27.076Z"
+---
+
+# 6 - Request Network in-house checkout (Rabby-supporting)
+
+- [x] 6 - Request Network in-house checkout (Rabby-supporting) #taskmaster #priority/high #status/done ⏫ 🆔 tm-6
+
+## Metadata
+
+| Field | Value |
+| --- | --- |
+| Taskmaster ID | 6 |
+| Status | done |
+| Priority | high |
+| Dependencies | None |
+| Parent | None |
+
+## Description
+
+Replace the redirect to pay.request.network with an Amanat-rendered checkout page that submits the same on-chain calls as RN's hosted UI, so RN's webhook fires unchanged but buyers stay on amn.gg and Rabby works.
+
+## Details
+
+See PRD: nick-doc/.taskmaster/docs/prd-request-network-in-house-checkout.md (summary at nick-doc/PRD - Request Network In-House Checkout.md). Status: draft, pending review with second developer. Approach: replicate the two on-chain calls (approve + RN_FEE_PROXY.transferFromWithReferenceAndFee) using wagmi v2 with existing injected()/metaMask() connectors (Rabby works via EIP-6963). Hard-known: proxy 0x0DfbEe143b42B41eFC5A6F87bFD1fFC78c2f0aC9, selector 0xc219a14d, paymentRef = last8Bytes(keccak256(requestId+salt+dest)), feeAmount=0, feeAddress=0x...dEaD. Backend: extend POST /payment/request-network/intents response with inHouseCheckout object (destination, tokenAddress, decimals, chainId, proxyAddress, paymentReference, feeAmount, feeAddress, amountWei). Frontend: new page /checkout/request-network/:paymentId with state machine reusing manual-payment.tsx layout chrome, hosted-page link kept as escape hatch. Implementation gated on a $0.50 cold probe on dev BSC to confirm RN's webhook fires for an externally-built tx. Out of scope: per-seller multi-chain config (§2), ephemeral wallets (§3), full RN removal (§4), gasless. Open questions in PRD §10.
+
+## Verification
+
+_No verification strategy._