擷取欄位，
知道該覆核哪些值。

curl -X POST https://api.space-ocr.com/ocr/fields \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "image": "https://example.com/receipt.jpg",
    "imageType": "url",
    "fields": [
      { "name": "store_name" },
      { "name": "invoice_no", "pattern": "^[0-9]{6}$" },
      { "name": "total", "type": "number", "required": true }
    ]
  }'

{
  "status": "success",
  "data": {
    "values": {
      "store_name": "Supermarket ABC",
      "invoice_no": "10O482",
      "total": "$4.94"
    },
    "cells": {
      "invoice_no": {
        "box": { "xmin": 612, "ymin": 96,
                 "xmax": 742, "ymax": 118 },
        "quad": [ /* 4 corners */ ],
        "verified": false,
        "review": { "reasons": ["pattern_mismatch"] },
        "evidence": { "text_match": true }
      }
      // …store_name, total — same shape
    },
    "review": {
      "unit": "field", "declared": 3,
      "returned": 3, "boxed": 3, "verified": 3,
      "flagged": [
        { "path": "invoice_no",
          "reasons": ["pattern_mismatch"] }
      ],
      "by_reason": { "pattern_mismatch": 1 }
    },
    "normalized": { "invoice_no": "10O482", "total": 4.94 },
    "image": { "width": 1654, "height": 2339 }
  }
}