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/repository/mongo/repository.go

@@ -192,6 +192,9 @@ func (r *Repository) GetCleanedBills(filter map[string]interface{}) ([]model.Cle
 		bsonFilter[k] = v
 	}
 
+	// 排除已删除的记录
+	bsonFilter["is_deleted"] = bson.M{"$ne": true}
+
 	// 按时间倒序排列
 	opts := options.Find().SetSort(bson.D{{Key: "time", Value: -1}})
 
@@ -220,6 +223,9 @@ func (r *Repository) GetCleanedBillsPaged(filter map[string]interface{}, page, p
 		bsonFilter[k] = v
 	}
 
+	// 排除已删除的记录
+	bsonFilter["is_deleted"] = bson.M{"$ne": true}
+
 	// 计算总数
 	total, err := r.cleanedCollection.CountDocuments(ctx, bsonFilter)
 	if err != nil {
@@ -260,6 +266,9 @@ func (r *Repository) GetBillsAggregate(filter map[string]interface{}) (totalExpe
 		bsonFilter[k] = v
 	}
 
+	// 排除已删除的记录
+	bsonFilter["is_deleted"] = bson.M{"$ne": true}
+
 	// 使用聚合管道按 income_expense 分组统计金额
 	pipeline := mongo.Pipeline{
 		{{Key: "$match", Value: bsonFilter}},
@@ -300,6 +309,7 @@ func (r *Repository) GetBillsAggregate(filter map[string]interface{}) (totalExpe
 func (r *Repository) GetBillsNeedReview() ([]model.CleanedBill, error) {
 	filter := map[string]interface{}{
 		"review_level": bson.M{"$in": []string{"HIGH", "LOW"}},
+		"is_deleted":   bson.M{"$ne": true},
 	}
 	return r.GetCleanedBills(filter)
 }
@@ -312,6 +322,8 @@ func (r *Repository) GetMonthlyStats() ([]model.MonthlyStat, error) {
 	// 使用聚合管道按月份分组统计
 	// 先按月份和收支类型分组，再汇总
 	pipeline := mongo.Pipeline{
+		// 排除已删除的记录
+		{{Key: "$match", Value: bson.M{"is_deleted": bson.M{"$ne": true}}}},
 		// 添加月份字段
 		{{Key: "$addFields", Value: bson.D{
 			{Key: "month", Value: bson.D{
@@ -418,6 +430,34 @@ func (r *Repository) UpdateCleanedBillByID(id string, updates map[string]interfa
 	return &updated, nil
 }
 
+// DeleteCleanedBillByID 按 ID 软删除清洗后的账单（设置 is_deleted = true）
+func (r *Repository) DeleteCleanedBillByID(id string) error {
+	if r.cleanedCollection == nil {
+		return fmt.Errorf("cleaned collection not initialized")
+	}
+
+	oid, err := primitive.ObjectIDFromHex(id)
+	if err != nil {
+		return fmt.Errorf("invalid id: %w", err)
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	filter := bson.M{"_id": oid}
+	update := bson.M{"$set": bson.M{"is_deleted": true}}
+	result, err := r.cleanedCollection.UpdateOne(ctx, filter, update)
+	if err != nil {
+		return fmt.Errorf("soft delete bill failed: %w", err)
+	}
+
+	if result.MatchedCount == 0 {
+		return repository.ErrNotFound
+	}
+
+	return nil
+}
+
 // GetClient 获取 MongoDB 客户端（用于兼容旧代码）
 func (r *Repository) GetClient() *mongo.Client {
 	return r.client

server/repository/repository.go

@@ -46,6 +46,9 @@ type BillRepository interface {
 	// UpdateCleanedBillByID 按 ID 更新清洗后的账单，并返回更新后的记录
 	UpdateCleanedBillByID(id string, updates map[string]interface{}) (*model.CleanedBill, error)
 
+	// DeleteCleanedBillByID 按 ID 删除清洗后的账单
+	DeleteCleanedBillByID(id string) error
+
 	// CountRawByField 按字段统计原始数据数量
 	CountRawByField(fieldName, value string) (int64, error)
 }