curl --request GET \
  --url https://api.anchorage-staging.com/v2/vesting/balances/{allocationId} \
  --header 'Api-Access-Key: <api-key>'

{
  "balance": {
    "assetType": "BTC",
    "availableBalance": "1000.50000000",
    "externalTokenId": "magna_token_123",
    "lockedBalance": "100.10000000",
    "networkId": "ETHHOODI",
    "unvestedBalance": "500.25000000"
  },
  "walletInfo": {
    "address": "0x1234567890abcdef...",
    "walletId": "3d293c0d64c703023692216e9b4f5280"
  }
}