refactor(exports, metadata): 更新行数估算逻辑和字段可见性以优化功能

- 修改create函数中的行数估算逻辑，确保在估算为0时使用精确COUNT进行统计
- 添加日志记录以跟踪估算过程，提升调试能力
- 更新metadata中的字段可见性，将绑定类型字段标记为隐藏，以符合新的业务需求
- 提升代码可读性，确保逻辑清晰明了

server/internal/api/exports.go

@@ -935,6 +935,7 @@ func transformRow(ds string, fields []string, vals []string) []string {
 			break
 		}
 		f := fields[i]
+		// 解密/转换订单 key
 		if f == "order.key" {
 			if ds == "ymt" {
 				key := os.Getenv("YMT_KEY_DECRYPT_KEY_B64")
@@ -948,6 +949,46 @@ func transformRow(ds string, fields []string, vals []string) []string {
 				vals[i] = decodeOrderKey(vals[i])
 			}
 		}
+		// voucher_batch.provider: 将渠道编码转换为中文名称
+		if f == "voucher_batch.provider" {
+			switch strings.TrimSpace(vals[i]) {
+			// 老编码
+			case "lsxd":
+				vals[i] = "蓝色兄弟"
+			case "fjxw":
+				vals[i] = "福建兴旺"
+			case "fzxy":
+				vals[i] = "福州兴雅"
+			case "fzyt":
+				vals[i] = "福州悦途"
+			// 新编码：微信立减金渠道
+			case "voucher_wechat_lsxd":
+				vals[i] = "蓝色兄弟"
+			case "voucher_wechat_fjxw":
+				vals[i] = "福建兴旺"
+			case "voucher_wechat_fzxy":
+				vals[i] = "福州兴雅"
+			case "voucher_wechat_fzyt":
+				vals[i] = "福州悦途"
+			case "voucher_wechat_zjky":
+				vals[i] = "浙江卡赢"
+			case "voucher_wechat_zjky2":
+				vals[i] = "浙江卡赢2"
+			case "voucher_wechat_zjwsxx":
+				vals[i] = "浙江喔刷"
+			case "voucher_wechat_gzynd":
+				vals[i] = "广州亿纳德"
+			case "voucher_wechat_fjhrxxfw":
+				vals[i] = "福建省宏仁信息服务"
+			case "voucher_wechat_fzqmkj":
+				vals[i] = "福州启蒙科技有限公司"
+			case "voucher_wechat_fzydxx":
+				vals[i] = "福州元朵信息科技有限公司"
+			case "voucher_wechat_xyhxx":
+				vals[i] = "新沂薪伙原信息科技有限公司"
+			}
+		}
+		// activity.channels: 解析 JSON 并转成可读渠道名
 		if f == "activity.channels" {
 			if vals[i] == "" || vals[i] == "0" {
 				vals[i] = "无"