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/content_assets.gen.go

@@ -17,15 +17,15 @@ const TableNameContentAsset = "content_assets"
 
 // ContentAsset mapped from table <content_assets>
 type ContentAsset struct {
-	ID        int64                   `gorm:"column:id;type:bigint;primaryKey;autoIncrement:true" json:"id"`
-	TenantID  int64                   `gorm:"column:tenant_id;type:bigint;not null" json:"tenant_id"`
-	UserID    int64                   `gorm:"column:user_id;type:bigint;not null" json:"user_id"`
-	ContentID int64                   `gorm:"column:content_id;type:bigint;not null" json:"content_id"`
-	AssetID   int64                   `gorm:"column:asset_id;type:bigint;not null" json:"asset_id"`
-	Role      consts.ContentAssetRole `gorm:"column:role;type:character varying(32);not null;default:main" json:"role"`
-	Sort      int32                   `gorm:"column:sort;type:integer;not null" json:"sort"`
-	CreatedAt time.Time               `gorm:"column:created_at;type:timestamp with time zone;not null;default:now()" json:"created_at"`
-	UpdatedAt time.Time               `gorm:"column:updated_at;type:timestamp with time zone;not null;default:now()" json:"updated_at"`
+	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；必须与 content_id、asset_id 所属租户一致" json:"tenant_id"`                           // 租户ID：多租户隔离；必须与 content_id、asset_id 所属租户一致
+	UserID    int64                   `gorm:"column:user_id;type:bigint;not null;comment:用户ID：操作人/绑定人；用于审计（通常为租户管理员或作者）" json:"user_id"`                                          // 用户ID：操作人/绑定人；用于审计（通常为租户管理员或作者）
+	ContentID int64                   `gorm:"column:content_id;type:bigint;not null;comment:内容ID：关联 contents.id；用于查询内容下资源列表" json:"content_id"`                                   // 内容ID：关联 contents.id；用于查询内容下资源列表
+	AssetID   int64                   `gorm:"column:asset_id;type:bigint;not null;comment:资源ID：关联 media_assets.id；用于查询资源归属内容" json:"asset_id"`                                    // 资源ID：关联 media_assets.id；用于查询资源归属内容
+	Role      consts.ContentAssetRole `gorm:"column:role;type:character varying(32);not null;default:main;comment:资源角色：main/cover/preview；preview 必须为独立资源以满足禁下载与防绕过" json:"role"` // 资源角色：main/cover/preview；preview 必须为独立资源以满足禁下载与防绕过
+	Sort      int32                   `gorm:"column:sort;type:integer;not null;comment:排序：同一 role 下的展示顺序，数值越小越靠前" json:"sort"`                                                    // 排序：同一 role 下的展示顺序，数值越小越靠前
+	CreatedAt time.Time               `gorm:"column:created_at;type:timestamp with time zone;not null;default:now();comment:创建时间：默认 now()；用于审计" json:"created_at"`                // 创建时间：默认 now()；用于审计
+	UpdatedAt time.Time               `gorm:"column:updated_at;type:timestamp with time zone;not null;default:now();comment:更新时间：默认 now()；更新 sort/role 时写入" json:"updated_at"`    // 更新时间：默认 now()；更新 sort/role 时写入
 }
 
 // Quick operations without importing query package