Check if Merkle Message is Executed

curl --request GET \
  --url https://data.spb.tac.build/tac/observer/is-message-executed

{
  "response": {
    "note": {
      "content": "<string>",
      "errorName": "<string>",
      "internalBytesError": "<string>",
      "internalMsg": "<string>"
    },
    "stage": "start",
    "success": true,
    "timestamp": 123,
    "transactions": [
      {
        "blockchainType": "TAC",
        "hash": "<string>"
      }
    ]
  }
}