NPS HTTP代理使用非标准的 401 响应进行认证，导致部分客户端（如浏览器插件）认证失败 #55
Description
问题描述：
当启用 NPS 的 HTTP 代理功能并设置用户名/密码认证时，通过配置了正确用户名和密码的浏览器代理插件（如 SwitchyOmega）访问网页失败，iOS系统无线HTTP代理同样访问失败。
失败场景：
使用浏览器插件通过 NPS 代理上网，网络抓包显示：
浏览器插件发送 CONNECT 请求到 NPS，不包含 Proxy-Authorization 头。
NPS 服务器响应 HTTP/1.1 401 Unauthorized，并包含 WWW-Authenticate: Basic realm="easyProxy" 头。
浏览器插件收到此响应后，没有重新发送带有 Proxy-Authorization 头的请求，导致连接失败。
成功场景 1 (curl + NPS)：
使用 curl 命令，并指定相同的用户名/密码 (curl -x http://user:pass@nps_ip:port ...)，可以成功通过 NPS 代理访问网页。网络抓包显示 curl 会直接发送包含 Proxy-Authorization 头的请求。
可使用的HTTP代理和NPS HTTP代理响应：
Hypertext Transfer Protocol
HTTP/1.1 407 Proxy Authentication Required
[Expert Info (Chat/Sequence): HTTP/1.1 407 Proxy Authentication Required]
[HTTP/1.1 407 Proxy Authentication Required]
[Severity level: Chat]
[Group: Sequence]
Response Version: HTTP/1.1
Status Code: 407
[Status Code Description: Proxy Authentication Required]
Response Phrase: Proxy Authentication Required
Proxy-Authenticate: Basic realm="SimpleProxyAuth"
Content-Length: 0
[Content length: 0]
Connection: close
[HTTP response 1/1]
[Time since request: 0.000443000 seconds]
[Request in frame: 4]
[Request URI: pss.bdstatic.com:443]
Hypertext Transfer Protocol
HTTP/1.1 401 Unauthorized
[Expert Info (Chat/Sequence): HTTP/1.1 401 Unauthorized]
[HTTP/1.1 401 Unauthorized]
[Severity level: Chat]
[Group: Sequence]
Response Version: HTTP/1.1
Status Code: 401
[Status Code Description: Unauthorized]
Response Phrase: Unauthorized
Content-Type: text/plain; charset=utf-8
WWW-Authenticate: Basic realm="easyProxy"
[HTTP response 1/1]
[Time since request: 0.000511000 seconds]
[Request in frame: 7]
[Request URI: pss.bdstatic.com:443]
File Data: 16 bytes