fix(wallet): allow relinking a pocket with an unfinished US bank link

[MakelangelOO]

Linear: BQE-2732

Why

A pocket whose US bank link was opened but never finished (creation_in_progress + pending_link) counts as "already has a bank": it disappears from the linkable pockets and the add-product picker, and stays blocked until the backend fails the attempt (~52h). The detail screen also shows the raw creation_in_progress status.

How it works

• New isPendingLinkUsBank and blocksUsBankLink: only usable or activating banks block a new link; failed and unfinished ones don't.
• Topup linkable pockets and the account-detail add-product picker use blocksUsBankLink.
• Retrying on that pocket sends the same ledgerId; the backend (bloque-app/payment-rails#994) reuses the open attempt or, if its token expired, closes it and creates a new one. No duplicate rows.
• Detail shows "Vinculación sin terminar" / "Linking not finished" for unfinished links.

Changes

• domain/accounts/external-us-bank.ts + tests
• routes/_authed/topup/us-banks/index.tsx, routes/_authed/accounts/$urn.tsx
• i18n es/en: accounts.detail.usBankPendingLink

Dev requirements

Merge only after bloque-app/payment-rails#994 is deployed. Without it, a retry can pick up an open attempt on a different pocket, or add a row next to the expired one.

Risk

Low. UI-only; a pocket with an unfinished link shows the link option again.

[linear]

BQE-2732