feat(admin): 密码校验统一与后台 API/设置增强

- 管理端账号/代理/站点等密码最短长度统一为 6 位
- LotterySettings、审计日志展示、币种与报表接口等小修复
- 补充设置批量更新、注单、校验错误等相关测试

app/Http/Controllers/Api/V1/Admin/Currency/AdminCurrencyUpdateController.php

@@ -25,10 +25,6 @@ final class AdminCurrencyUpdateController extends Controller
             $data['is_bettable'] = (bool) $data['is_bettable'];
         }
 
-        if (array_key_exists('decimal_places', $data)) {
-            $data['decimal_places'] = (int) $data['decimal_places'];
-        }
-
         if (array_key_exists('is_enabled', $data)) {
             $data['is_enabled'] = (bool) $data['is_enabled'];
         }