feat: add balance and ledger endpoints for tenant

- Implemented MyBalance and MyLedgerPage methods in the ledger service to retrieve current user balance and transaction history for a specified tenant.
- Added corresponding test cases for MyBalance and MyLedgerPage methods in the ledger test suite.
- Created DTOs for balance response and ledger items to structure the response data.
- Updated Swagger documentation to include new endpoints for retrieving tenant balance and ledgers.
- Added HTTP tests for the new endpoints to ensure proper functionality.

backend/docs/swagger.yaml

@@ -116,6 +116,22 @@ definitions:
     x-enum-varnames:
     - RoleUser
     - RoleSuperAdmin
+  consts.TenantLedgerType:
+    enum:
+    - credit_topup
+    - debit_purchase
+    - credit_refund
+    - freeze
+    - unfreeze
+    - adjustment
+    type: string
+    x-enum-varnames:
+    - TenantLedgerTypeCreditTopup
+    - TenantLedgerTypeDebitPurchase
+    - TenantLedgerTypeCreditRefund
+    - TenantLedgerTypeFreeze
+    - TenantLedgerTypeUnfreeze
+    - TenantLedgerTypeAdjustment
   consts.TenantStatus:
     enum:
     - pending_verify
@@ -317,6 +333,22 @@ definitions:
       token:
         type: string
     type: object
+  dto.MeBalanceResponse:
+    properties:
+      balance:
+        description: Balance 可用余额：可用于购买/消费。
+        type: integer
+      balance_frozen:
+        description: BalanceFrozen 冻结余额：用于下单冻结/争议期等。
+        type: integer
+      currency:
+        allOf:
+        - $ref: '#/definitions/consts.Currency'
+        description: Currency 币种：当前固定 CNY（金额单位为分）。
+      updated_at:
+        description: UpdatedAt 更新时间：余额变更时更新。
+        type: string
+    type: object
   dto.MeResponse:
     properties:
       tenant:
@@ -333,6 +365,16 @@ definitions:
         - $ref: '#/definitions/models.User'
         description: User is the authenticated user derived from JWT `user_id`.
     type: object
+  dto.MyLedgerItem:
+    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.PurchaseContentForm:
     properties:
       idempotency_key:
@@ -809,6 +851,54 @@ definitions:
       uuid:
         type: string
     type: object
+  models.TenantLedger:
+    properties:
+      amount:
+        description: 流水金额：分/最小货币单位；通常为正数，方向由 type 决定（由业务层约束）
+        type: integer
+      balance_after:
+        description: 变更后可用余额：用于审计与对账回放
+        type: integer
+      balance_before:
+        description: 变更前可用余额：用于审计与对账回放
+        type: integer
+      created_at:
+        description: 创建时间：默认 now()
+        type: string
+      frozen_after:
+        description: 变更后冻结余额：用于审计与对账回放
+        type: integer
+      frozen_before:
+        description: 变更前冻结余额：用于审计与对账回放
+        type: integer
+      id:
+        description: 主键ID：自增
+        type: integer
+      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
+      order:
+        $ref: '#/definitions/models.Order'
+      order_id:
+        description: 关联订单ID：购买/退款类流水应关联 orders.id；非订单类可为空
+        type: integer
+      remark:
+        description: 备注：业务说明/后台操作原因等；用于审计
+        type: string
+      tenant_id:
+        description: 租户ID：多租户隔离关键字段；必须与 tenant_users.tenant_id 一致
+        type: integer
+      type:
+        allOf:
+        - $ref: '#/definitions/consts.TenantLedgerType'
+        description: 流水类型：credit_topup/debit_purchase/credit_refund/freeze/unfreeze/adjustment；不同类型决定余额/冻结余额的变更方向
+      updated_at:
+        description: 更新时间：默认 now()
+        type: string
+      user_id:
+        description: 用户ID：余额账户归属用户；对应 tenant_users.user_id
+        type: integer
+    type: object
   models.TenantUser:
     properties:
       balance:
@@ -1600,6 +1690,51 @@ paths:
       summary: 当前租户上下文信息
       tags:
       - Tenant
+  /t/{tenantCode}/v1/me/balance:
+    get:
+      consumes:
+      - application/json
+      parameters:
+      - description: Tenant Code
+        in: path
+        name: tenantCode
+        required: true
+        type: string
+      produces:
+      - application/json
+      responses:
+        "200":
+          description: OK
+          schema:
+            $ref: '#/definitions/dto.MeBalanceResponse'
+      summary: 当前租户余额信息
+      tags:
+      - Tenant
+  /t/{tenantCode}/v1/me/ledgers:
+    get:
+      consumes:
+      - application/json
+      parameters:
+      - description: Tenant Code
+        in: path
+        name: tenantCode
+        required: true
+        type: string
+      produces:
+      - application/json
+      responses:
+        "200":
+          description: OK
+          schema:
+            allOf:
+            - $ref: '#/definitions/requests.Pager'
+            - properties:
+                items:
+                  $ref: '#/definitions/dto.MyLedgerItem'
+              type: object
+      summary: 当前租户余额流水（分页）
+      tags:
+      - Tenant
   /t/{tenantCode}/v1/orders:
     get:
       consumes: