Add Daily Performance Summary REST API #559

{
  "period": "Today",
  "fromDate": "2026-06-28T00:00:00Z",
  "toDate": "2026-06-28T23:59:59Z",
  "periodLabel": "Today",
  "metrics": [
    {
      "title": "Total transaction count",
      "value": "48",
      "description": "Processed today",
      "category": "Total"
    },
    {
      "title": "Total transaction value",
      "value": "10,250.00 KES",
      "description": "Gross value",
      "category": "Total"
    },
    {
      "title": "Successful transaction count",
      "value": "44",
      "description": "Completed successfully",
      "category": "Success"
    },
    {
      "title": "Failed transaction count",
      "value": "4",
      "description": "Could not be completed",
      "category": "Failure"
    },
    {
      "title": "Average transaction value",
      "value": "213.54 KES",
      "description": "Average across all transactions",
      "category": "Neutral"
    },
    {
      "title": "Top product",
      "value": "Mobile Topup",
      "description": "Highest volume",
      "category": "Neutral"
    }
  ],
  "drillDownTransactions": [
    {
      "reference": "TXN-00048",
      "product": "Mobile Topup",
      "status": "Success",
      "amount": "250.00 KES",
      "transactionDateTime": "2026-06-28T09:15:00Z"
    },
    {
      "reference": "TXN-00047",
      "product": "Bill Payment",
      "status": "Success",
      "amount": "1,500.00 KES",
      "transactionDateTime": "2026-06-28T08:15:00Z"
    },
    {
      "reference": "TXN-00046",
      "product": "Voucher Issue",
      "status": "Failed",
      "amount": "0.00 KES",
      "transactionDateTime": "2026-06-28T07:15:00Z"
    }
  ]
}