feat: 添加账单软删除功能

- 新增删除按钮（带二次确认）到账单详情抽屉
- 后端实现软删除（设置 is_deleted 标记）
- 所有查询方法自动过滤已删除记录
- 账单列表和复核页面都支持删除
- 版本更新至 1.2.0

server/handler/delete_bill.go

@@ -0,0 +1,42 @@
+package handler
+
+import (
+	"net/http"
+	"strings"
+
+	"github.com/gin-gonic/gin"
+
+	"billai-server/repository"
+)
+
+type DeleteBillResponse struct {
+	Result  bool   `json:"result"`
+	Message string `json:"message,omitempty"`
+}
+
+// DeleteBill DELETE /api/bills/:id 删除清洗后的账单记录
+func DeleteBill(c *gin.Context) {
+	id := strings.TrimSpace(c.Param("id"))
+	if id == "" {
+		c.JSON(http.StatusBadRequest, DeleteBillResponse{Result: false, Message: "缺少账单 ID"})
+		return
+	}
+
+	repo := repository.GetRepository()
+	if repo == nil {
+		c.JSON(http.StatusInternalServerError, DeleteBillResponse{Result: false, Message: "数据库未连接"})
+		return
+	}
+
+	err := repo.DeleteCleanedBillByID(id)
+	if err != nil {
+		if err == repository.ErrNotFound {
+			c.JSON(http.StatusNotFound, DeleteBillResponse{Result: false, Message: "账单不存在"})
+			return
+		}
+		c.JSON(http.StatusInternalServerError, DeleteBillResponse{Result: false, Message: "删除失败: " + err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusOK, DeleteBillResponse{Result: true, Message: "删除成功"})
+}

server/handler/update_bill.go

@@ -23,6 +23,7 @@ type UpdateBillRequest struct {
 	PayMethod     *string  `json:"pay_method,omitempty"`
 	Status        *string  `json:"status,omitempty"`
 	Remark        *string  `json:"remark,omitempty"`
+	ReviewLevel   *string  `json:"review_level,omitempty"`
 }
 
 type UpdateBillResponse struct {
@@ -119,6 +120,16 @@ func UpdateBill(c *gin.Context) {
 		updates["remark"] = strings.TrimSpace(*req.Remark)
 	}
 
+	if req.ReviewLevel != nil {
+		// 允许设置为空字符串（清除复核等级）或 HIGH/LOW
+		v := strings.TrimSpace(*req.ReviewLevel)
+		if v != "" && v != "HIGH" && v != "LOW" {
+			c.JSON(http.StatusBadRequest, UpdateBillResponse{Result: false, Message: "review_level 只能是空、HIGH 或 LOW"})
+			return
+		}
+		updates["review_level"] = v
+	}
+
 	if len(updates) == 0 {
 		c.JSON(http.StatusBadRequest, UpdateBillResponse{Result: false, Message: "没有可更新的字段"})
 		return