Expected JSON format: either an array of accounts or an object with an accounts array. For institutions, use institution_name — ✨ AI-powered matching: abbreviations (ICBC), different languages (中银香港), and name variations will be matched automatically.

[
  {
    "name": "Checking USD",
    "account_number": "****1234",                        // optional
    "currency_code": "USD",
    "account_type": "bank_checking",
    "balance": 1234.56,
    "institution_name": "ICBC",                                // optional, AI matches "ICBC" → "中国工商银行"
    "note": "Imported from JSON"                               // optional
  }
]