fix(fiat-payout): send bank account category to airwallex

Why

On staging, adding a bank account for a USD withdrawal failed with 422 BENEFICIARY_REJECTED. Airwallex POST /api/v1/beneficiaries/create returned validation_failed on beneficiary.bank_details.bank_account_category: the field is required for US ACH beneficiaries, and we did not send it.

Probing /api/v1/beneficiaries/validate on the sandbox, which creates nothing:

• missing → 400;
• CHECKING → 400 (value_options: ["Checking","Savings"]);
• Checking → 200;
• Savings → 200.

The values are case-sensitive.

What

• BE: CreateBankBeneficiaryDto.accountCategory is required and accepts only CHECKING or SAVINGS. AirwallexPayoutClient maps it to Checking or Savings in bank_details.bank_account_category.
• FE: "Account type" choice (Checking / Savings, default Checking) on the add-bank screen. The generated model is hand-edited to match the orval output, because staging swagger does not have the field yet.
• No DB column and no migration: the category is only needed when the beneficiary is created.

Compatibility

App builds that predate this change get a 400 from the new required field. No build with the bank-withdrawal screens has shipped to users, so nothing in the field breaks.

Tests

• BE: yarn jest src/modules/fiat-payout passes (207 tests). yarn build and eslint are clean.
• FE: pnpm jest src/components/withdraw passes (47 tests), including a new add-bank screen test. tsc and eslint are clean.
• Mutation-checked: each new assertion fails when the mapping or the default is broken.

Opus review gate: PASS in round 1, with 0 blocking, 0 should-fix and 3 nits. The nits are parked:

• the radio pill should use accessibilityState.checked rather than selected;
• import type for BankAccountCategory;
• the inline selector is verbose.

After merge

Retest on staging: add a bank account (routing 021000021), withdraw $11, then simulate PAID and FAILED in the Airwallex sandbox.

🤖 Generated with Claude Code