feat: add operator and business reference fields to tenant ledgers

- Added `operator_user_id`, `biz_ref_type`, and `biz_ref_id` fields to the TenantLedger model for enhanced auditing and traceability.
- Updated the tenant ledgers query generation to include new fields.
- Introduced new API endpoint for retrieving tenant ledger records with filtering options based on the new fields.
- Enhanced Swagger documentation to reflect the new endpoint and its parameters.
- Created DTOs for admin ledger filtering and item representation.
- Implemented the admin ledger retrieval logic in the tenant service.
- Added database migration scripts to introduce new fields and indexes for efficient querying.

backend/docs/swagger.yaml

@@ -257,6 +257,16 @@ definitions:
         description: UserID 目标用户ID。
         type: integer
     type: object
+  dto.AdminLedgerItem:
+    properties:
+      ledger:
+        allOf:
+        - $ref: '#/definitions/models.TenantLedger'
+        description: Ledger 流水记录（租户内隔离）。
+      type_description:
+        description: TypeDescription 流水类型中文说明（用于前端展示）。
+        type: string
+    type: object
   dto.AdminMediaAssetUploadCompleteForm:
     properties:
       content_type:
@@ -1054,10 +1064,9 @@ definitions:
         description: 退款完成时间：退款落账成功后写入
         type: string
       snapshot:
+        allOf:
+        - $ref: '#/definitions/types.JSONType-fields_OrdersSnapshot'
         description: 订单快照：JSON；建议包含 content 标题/定价/折扣、请求来源等，避免改价影响历史展示
-        items:
-          type: integer
-        type: array
       status:
         allOf:
         - $ref: '#/definitions/consts.OrderStatus'
@@ -1101,10 +1110,9 @@ definitions:
         description: 订单ID：关联 orders.id；用于聚合订单明细
         type: integer
       snapshot:
+        allOf:
+        - $ref: '#/definitions/types.JSONType-fields_OrderItemsSnapshot'
         description: 内容快照：JSON；建议包含 title/price/discount 等，用于历史展示与审计
-        items:
-          type: integer
-        type: array
       tenant_id:
         description: 租户ID：多租户隔离关键字段；必须与 orders.tenant_id 一致
         type: integer
@@ -1232,6 +1240,12 @@ definitions:
       balance_before:
         description: 变更前可用余额：用于审计与对账回放
         type: integer
+      biz_ref_id:
+        description: 业务引用ID：与 biz_ref_type 配合使用（例如 orders.id）；用于对账与审计
+        type: integer
+      biz_ref_type:
+        description: 业务引用类型：order/refund/topup/etc；与 biz_ref_id 组成可选的结构化幂等/追溯键
+        type: string
       created_at:
         description: 创建时间：默认 now()
         type: string
@@ -1247,6 +1261,9 @@ definitions:
       idempotency_key:
         description: 幂等键：同一租户同一用户同一业务操作固定；用于防止重复落账（建议由业务层生成）
         type: string
+      operator_user_id:
+        description: 操作者用户ID：谁触发该流水（admin/buyer/system）；用于审计与追责；可为空（历史数据或无法识别时）
+        type: integer
       order:
         $ref: '#/definitions/models.Order'
       order_id:
@@ -1350,6 +1367,10 @@ definitions:
           paging).
         type: integer
     type: object
+  types.JSONType-fields_OrderItemsSnapshot:
+    type: object
+  types.JSONType-fields_OrdersSnapshot:
+    type: object
 externalDocs:
   description: OpenAPI
   url: https://swagger.io/resources/open-api/
@@ -1967,6 +1988,92 @@ paths:
       summary: 拒绝加入申请（租户管理）
       tags:
       - Tenant
+  /t/{tenantCode}/v1/admin/ledgers:
+    get:
+      consumes:
+      - application/json
+      parameters:
+      - description: Tenant Code
+        in: path
+        name: tenantCode
+        required: true
+        type: string
+      - description: BizRefID 按业务引用ID过滤（可选）。
+        in: query
+        name: biz_ref_id
+        type: integer
+      - description: |-
+          BizRefType 按业务引用类型过滤（可选）。
+          约定：当前业务写入为 "order"；未来可扩展为 refund/topup 等。
+        in: query
+        name: biz_ref_type
+        type: string
+      - description: CreatedAtFrom 创建时间起（可选）。
+        in: query
+        name: created_at_from
+        type: string
+      - description: CreatedAtTo 创建时间止（可选）。
+        in: query
+        name: created_at_to
+        type: string
+      - description: Limit is page size; only values in {10,20,50,100} are accepted
+          (otherwise defaults to 10).
+        in: query
+        name: limit
+        type: integer
+      - description: |-
+          OperatorUserID 按操作者用户ID过滤（可选）。
+          典型场景：后台检索“某个管理员发起的充值/退款”等敏感操作流水。
+        in: query
+        name: operator_user_id
+        type: integer
+      - description: OrderID 按关联订单过滤（可选）。
+        in: query
+        name: order_id
+        type: integer
+      - description: Page is 1-based page index; values <= 0 are normalized to 1.
+        in: query
+        name: page
+        type: integer
+      - description: Type 按流水类型过滤（可选）。
+        enum:
+        - credit_topup
+        - debit_purchase
+        - credit_refund
+        - freeze
+        - unfreeze
+        - adjustment
+        in: query
+        name: type
+        type: string
+        x-enum-varnames:
+        - TenantLedgerTypeCreditTopup
+        - TenantLedgerTypeDebitPurchase
+        - TenantLedgerTypeCreditRefund
+        - TenantLedgerTypeFreeze
+        - TenantLedgerTypeUnfreeze
+        - TenantLedgerTypeAdjustment
+      - description: |-
+          UserID 按余额账户归属用户ID过滤（可选）。
+          典型场景：查看某个租户成员的资金变化全链路。
+        in: query
+        name: user_id
+        type: integer
+      produces:
+      - application/json
+      responses:
+        "200":
+          description: OK
+          schema:
+            allOf:
+            - $ref: '#/definitions/requests.Pager'
+            - properties:
+                items:
+                  $ref: '#/definitions/dto.AdminLedgerItem'
+              type: object
+      summary: 余额流水列表（租户管理/审计）
+      tags:
+      - Tenant
   /t/{tenantCode}/v1/admin/media_assets:
     get:
       consumes: