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/tests/tenant.http

@@ -12,6 +12,16 @@ GET {{ host }}/t/{{ tenantCode }}/v1/me
 Content-Type: application/json
 Authorization: Bearer {{ token }}
 
+### Tenant - My balance
+GET {{ host }}/t/{{ tenantCode }}/v1/me/balance
+Content-Type: application/json
+Authorization: Bearer {{ token }}
+
+### Tenant - My ledgers (paged)
+GET {{ host }}/t/{{ tenantCode }}/v1/me/ledgers?page=1&limit=20
+Content-Type: application/json
+Authorization: Bearer {{ token }}
+
 ### Tenant - Contents list (published)
 GET {{ host }}/t/{{ tenantCode }}/v1/contents?page=1&limit=10
 Content-Type: application/json