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/Models/Invoice.cs

@@ -0,0 +1,66 @@
+namespace AgriculturalPlatform.Api.Models;
+
+/// <summary>农产品反向开票（收购发票：收购方向农户开具）</summary>
+public class Invoice
+{
+    public int Id { get; set; }
+
+    /// <summary>发票号码（如 FP20260812-0001）</summary>
+    public string InvoiceNo { get; set; } = string.Empty;
+
+    /// <summary>开票批次号（批量开票时同一批共用）</summary>
+    public string BatchNo { get; set; } = string.Empty;
+
+    /// <summary>票种：农产品收购发票</summary>
+    public string InvoiceKind { get; set; } = "农产品收购发票";
+
+    /// <summary>销售方（农户）</summary>
+    public int FarmerId { get; set; }
+
+    public Farmer? Farmer { get; set; }
+
+    /// <summary>收购方（公司/站/个体）</summary>
+    public int PurchaserOrgId { get; set; }
+
+    public Organization? PurchaserOrg { get; set; }
+
+    /// <summary>关联收购单（可空）</summary>
+    public int? PurchaseOrderId { get; set; }
+
+    public PurchaseOrder? PurchaseOrder { get; set; }
+
+    /// <summary>品名（冗余，便于发票展示）</summary>
+    public int ProductId { get; set; }
+
+    public Product? Product { get; set; }
+
+    /// <summary>数量</summary>
+    public decimal Quantity { get; set; }
+
+    public string Unit { get; set; } = "公斤";
+
+    public decimal UnitPrice { get; set; }
+
+    /// <summary>价税合计（元）</summary>
+    public decimal Amount { get; set; }
+
+    /// <summary>税率（%），农产品收购发票免税为 0</summary>
+    public decimal TaxRate { get; set; } = 0m;
+
+    public decimal TaxAmount { get; set; }
+
+    public DateTime IssueDate { get; set; } = DateTime.Now;
+
+    public InvoiceStatus Status { get; set; } = InvoiceStatus.Issued;
+
+    /// <summary>开票人</summary>
+    public int? OperatorId { get; set; }
+
+    public User? Operator { get; set; }
+
+    public DateTime? ReversedAt { get; set; }
+
+    public string ReverseReason { get; set; } = string.Empty;
+
+    public DateTime CreatedAt { get; set; } = DateTime.Now;
+}