Retrieve the curated top banks for a market. `country` selects the market; optional `currency` filters further; `limit` caps the result count. Public and cacheable at the market level.

Example response

{
  "success": true,
  "data": {
    "banks": [
      {
        "id": "123e4567-e89b-12d3-a456-426614174001",
        "name": "Santander",
        "market": "GB",
        "currency": "GBP",
        "displayName": "Santander",
        "logoUrl": "https://example.com/logo.png",
        "websiteUrl": "https://www.santander.co.uk",
        "topInMarket": true
      }
    ]
  }
}