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-11.md

@@ -0,0 +1,35 @@
+---
+taskmaster_id: "11"
+status: "pending"
+priority: "high"
+depends_on: []
+parent_id: ""
+source: "taskmaster"
+generated_at: "2026-05-28T11:49:27.076Z"
+---
+
+# 11 - Trezor signing for admin actions (release/refund/sweep)
+
+- [ ] 11 - Trezor signing for admin actions (release/refund/sweep) #taskmaster #priority/high #status/pending ⏫ 🆔 tm-11
+
+## Metadata
+
+| Field | Value |
+| --- | --- |
+| Taskmaster ID | 11 |
+| Status | pending |
+| Priority | high |
+| Dependencies | None |
+| Parent | None |
+
+## Description
+
+Replace the hot-key admin signing flow with a WebUSB-based Trezor flow so the backend never holds a private key. All admin-side txes are built backend, signed via Trezor in the browser, broadcast from the browser.
+
+## Details
+
+See PRD - Wallet, Multichain, Confirmations, AML, Trezor.md §5. Lib: @trezor/connect-web (WebUSB; Chromium-only — Firefox users need Trezor Bridge native helper). Files: new frontend/src/web3/trezor/trezorConnector.ts wrapping @trezor/connect-web; existing admin actions (release/refund/sweep when #7 lands) get a 'Sign with Trezor' button that flows: POST /api/admin/actions/build-tx → returns unsigned tx bytes → send to Trezor → sign → wagmi sendTransaction broadcasts → POST /api/admin/actions/confirm-tx with hash; admin settings page to register Trezor address(es) (backend rejects signatures from unauthorized devices); audit log on every Trezor-signed action; break-glass hot-key path requires explicit admin toggle, expires after 1h, fires Telegram alarm. Open questions: m-of-n multi-admin signing — default single-signer for v1; Trezor One vs Model T — lib abstracts; fallback when Trezor unavailable — break-glass with alarm. Acceptance: admin registers Trezor address; release flow uses Trezor end-to-end; backend rejects signatures from unregistered devices; audit log captures admin user + Trezor addr + tx hash + before/after escrow state; break-glass works and alarms. Non-goals: mobile Trezor flow, buyer-side Trezor (buyer uses wagmi injected). Dependencies: task #7 (ephemeral wallets) for the sweep step — but task #11 can ship the release/refund flows first. This is task #11 in the PRD.
+
+## Verification
+
+_No verification strategy._