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>

02 - Data Models/Payment.md

@@ -55,6 +55,7 @@ Records every monetary movement in the marketplace: buyer pay-ins, seller payout
 | `metadata.requestNetworkPaymentReference` | String | no | — | — | — | Request Network payment reference. |
 | `metadata.requestNetworkSecurePaymentUrl` | String | no | — | — | — | Request Network secure payment URL. |
 | `metadata.requestNetworkData` | Mixed | no | — | — | — | Raw Request Network payload. |
+| `metadata.transactionSafety` | Mixed | no | — | — | — | Last Transaction Safety Provider decision, checks, evidence, and blocker reason. |
 | `metadata.lastWebhookAt` | Date | no | — | — | — | Last webhook timestamp. |
 | `metadata.webhookPayload` | Mixed | no | — | — | — | Last webhook body. |
 | `metadata.createdVia` | String | no | — | — | — | Origin marker. |