fix(mining-wallet-service): pool-account GET :type 改为 @Public() 允许内网服务间调用

mining-admin-service 通过 fetch 查询余额时无 token，@AdminOnly() 导致 401，UI 始终显示 0.00

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

backend/services/mining-wallet-service/src/api/controllers/pool-account.controller.ts

@@ -58,8 +58,8 @@ export class PoolAccountController {
   }
 
   @Get(':type')
-  @AdminOnly()
-  @ApiOperation({ summary: '获取特定类型池账户' })
+  @Public()
+  @ApiOperation({ summary: '获取特定类型池账户（内网服务间调用）' })
   async findByType(@Param('type') type: PoolAccountType) {
     return this.poolAccountService.findByType(type);
   }