新增农户功能升级：身份证OCR/OSS上传、头像采集、同名村检测、Region热度排序及表单体验优化

- Region 表新增热度列，热门省份优先显示
- 区县下拉按地级市分组、已录区县优先、支持全省搜索
- 组选择内置一组至二十组
- 银行卡号独立行+粗体预览，开户行独立行
- 新增农户类型：农户/个体户/合作社/经营集体/公司
- 身份证正反面支持高拍仪/摄像头OCR与手机扫码上传，附件存本地/OSS
- 新增农户头像采集组件（摄像头/本地上传），预留人脸识别收购扩展
- 同名村弹窗提醒（防选错乡镇）
- 编辑窗体禁止遮罩/Esc误关，整体加宽适配高频操作
- 修复二维码局域网手机无法访问（监听0.0.0.0、局域网IP识别、Vite代理兜底）

backend/AgriculturalPlatform.Api/Dtos/PurchaseDtos.cs

@@ -0,0 +1,32 @@
+using AgriculturalPlatform.Api.Models;
+
+namespace AgriculturalPlatform.Api.Dtos;
+
+public record PurchaseDto(
+    int Id, string OrderNo, int FarmerId, string FarmerName, string? FarmerPhone,
+    int ProductId, string ProductName, string Category, int PurchaserOrgId, string PurchaserOrgName,
+    string Grade, string Unit, decimal UnitPrice, decimal GrossWeight, decimal TareWeight,
+    decimal NetWeight, decimal Amount, int WeighCount, string Status,
+    string? OperatorName, DateTime WeighInAt, DateTime? WeighOutAt, string Notes, DateTime CreatedAt);
+
+/// <summary>新建收购单（第一次过磅：称毛重）</summary>
+public record PurchaseCreateRequest(
+    int FarmerId, int ProductId, int PurchaserOrgId, string Grade,
+    decimal GrossWeight, string Unit = "公斤", decimal UnitPrice = 0, string Notes = "");
+
+/// <summary>回皮完成（第二次过磅：称皮重，计算净重与金额）</summary>
+public record PurchaseTareRequest(decimal TareWeight);
+
+public static class PurchaseMappers
+{
+    public static PurchaseDto ToDto(this PurchaseOrder p) => new(
+        p.Id, p.OrderNo,
+        p.FarmerId, p.Farmer?.Name ?? "", p.Farmer?.Phone ?? "",
+        p.ProductId, p.Product?.Name ?? "", p.Product?.Category ?? "",
+        p.PurchaserOrgId, p.PurchaserOrg?.Name ?? "",
+        p.Grade, p.Unit, p.UnitPrice, p.GrossWeight, p.TareWeight,
+        p.NetWeight, p.Amount, p.WeighCount, p.Status.ToString(),
+        p.Operator?.RealName ?? "", p.WeighInAt, p.WeighOutAt, p.Notes, p.CreatedAt);
+
+    public static PurchaseDto[] ToDtos(this IEnumerable<PurchaseOrder> items) => items.Select(ToDto).ToArray();
+}