fix(服务自检): 修复 DNSCheck.psm1 编码问题 - 添加 UTF-8 BOM

- DNSCheck.psm1 缺少 UTF-8 BOM 导致 PowerShell 解析失败
- 添加 BOM 后所有 16 个模块加载验证通过
Co-Authored-By: Claude <noreply@anthropic.com>

AuxiliaryTool/ScriptTool/ServiceSelfInspection/modules/DNSCheck.psm1

-# ==============================================================================
+# ==============================================================================
 # DNSCheck.psm1
 # ------------------------------------------------------------------------------
 # DNS 检测模块