fix(mining-admin-service): cast response.data to any for envelope unwrapping

TypeScript build fails because MiningServiceResponse type doesn't have
a 'data' property. The runtime response from mining-service wraps data
in a { success, data } envelope, so we need `as any` to access it.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/services/mining-admin-service/src/application/services/system-accounts.service.ts

@@ -47,7 +47,7 @@ export class SystemAccountsService {
       );
 
       const miningDataMap = new Map<string, MiningServiceSystemAccount>();
-      const body = response.data?.data ?? response.data;
+      const body = (response.data as any)?.data ?? response.data;
       for (const account of body.accounts) {
         // 使用 accountType:regionCode 作为 key，与 contribution 表一致
         const key = account.regionCode