feat: add TenantLedger model and query generation

- Introduced TenantLedger model with fields for managing tenant transactions, including ID, TenantID, UserID, OrderID, transaction Type, Amount, and balance details.
- Implemented CRUD operations for TenantLedger with methods for Create, Update, Delete, and Reload.
- Generated query methods for TenantLedger to facilitate database interactions, including filtering, pagination, and aggregation functions.
- Established relationships with Order model for foreign key references.

backend/database/models/order_items.gen.go

@@ -0,0 +1,63 @@
+// Code generated by go.ipao.vip/gen. DO NOT EDIT.
+// Code generated by go.ipao.vip/gen. DO NOT EDIT.
+// Code generated by go.ipao.vip/gen. DO NOT EDIT.
+
+package models
+
+import (
+	"context"
+	"time"
+
+	"go.ipao.vip/gen"
+	"go.ipao.vip/gen/types"
+)
+
+const TableNameOrderItem = "order_items"
+
+// OrderItem mapped from table <order_items>
+type OrderItem struct {
+	ID            int64      `gorm:"column:id;type:bigint;primaryKey;autoIncrement:true;comment:主键ID：自增" json:"id"`                                          // 主键ID：自增
+	TenantID      int64      `gorm:"column:tenant_id;type:bigint;not null;comment:租户ID：多租户隔离关键字段；必须与 orders.tenant_id 一致" json:"tenant_id"`                  // 租户ID：多租户隔离关键字段；必须与 orders.tenant_id 一致
+	UserID        int64      `gorm:"column:user_id;type:bigint;not null;comment:用户ID：下单用户（buyer）；冗余字段用于查询加速与审计" json:"user_id"`                              // 用户ID：下单用户（buyer）；冗余字段用于查询加速与审计
+	OrderID       int64      `gorm:"column:order_id;type:bigint;not null;comment:订单ID：关联 orders.id；用于聚合订单明细" json:"order_id"`                                // 订单ID：关联 orders.id；用于聚合订单明细
+	ContentID     int64      `gorm:"column:content_id;type:bigint;not null;comment:内容ID：关联 contents.id；用于生成/撤销 content_access" json:"content_id"`            // 内容ID：关联 contents.id；用于生成/撤销 content_access
+	ContentUserID int64      `gorm:"column:content_user_id;type:bigint;not null;comment:内容作者用户ID：用于后续分成/对账扩展；当前可为 0 或写入内容创建者" json:"content_user_id"`        // 内容作者用户ID：用于后续分成/对账扩展；当前可为 0 或写入内容创建者
+	AmountPaid    int64      `gorm:"column:amount_paid;type:bigint;not null;comment:该行实付金额：分；通常等于订单 amount_paid（单内容场景）" json:"amount_paid"`                  // 该行实付金额：分；通常等于订单 amount_paid（单内容场景）
+	Snapshot      types.JSON `gorm:"column:snapshot;type:jsonb;not null;default:{};comment:内容快照：JSON；建议包含 title/price/discount 等，用于历史展示与审计" json:"snapshot"` // 内容快照：JSON；建议包含 title/price/discount 等，用于历史展示与审计
+	CreatedAt     time.Time  `gorm:"column:created_at;type:timestamp with time zone;not null;default:now();comment:创建时间：默认 now()" json:"created_at"`         // 创建时间：默认 now()
+	UpdatedAt     time.Time  `gorm:"column:updated_at;type:timestamp with time zone;not null;default:now();comment:更新时间：默认 now()" json:"updated_at"`         // 更新时间：默认 now()
+	Order         *Order     `gorm:"foreignKey:OrderID;references:ID" json:"order,omitempty"`
+	Content       *Content   `gorm:"foreignKey:ContentID;references:ID" json:"content,omitempty"`
+}
+
+// Quick operations without importing query package
+// Update applies changed fields to the database using the default DB.
+func (m *OrderItem) Update(ctx context.Context) (gen.ResultInfo, error) {
+	return Q.OrderItem.WithContext(ctx).Updates(m)
+}
+
+// Save upserts the model using the default DB.
+func (m *OrderItem) Save(ctx context.Context) error { return Q.OrderItem.WithContext(ctx).Save(m) }
+
+// Create inserts the model using the default DB.
+func (m *OrderItem) Create(ctx context.Context) error { return Q.OrderItem.WithContext(ctx).Create(m) }
+
+// Delete removes the row represented by the model using the default DB.
+func (m *OrderItem) Delete(ctx context.Context) (gen.ResultInfo, error) {
+	return Q.OrderItem.WithContext(ctx).Delete(m)
+}
+
+// ForceDelete permanently deletes the row (ignores soft delete) using the default DB.
+func (m *OrderItem) ForceDelete(ctx context.Context) (gen.ResultInfo, error) {
+	return Q.OrderItem.WithContext(ctx).Unscoped().Delete(m)
+}
+
+// Reload reloads the model from database by its primary key and overwrites current fields.
+func (m *OrderItem) Reload(ctx context.Context) error {
+	fresh, err := Q.OrderItem.WithContext(ctx).GetByID(m.ID)
+	if err != nil {
+		return err
+	}
+	*m = *fresh
+	return nil
+}