feat: dsh-lan-access — 局域网访问 dsh Web UI

用独立反向代理把 dsh Web UI 发布到局域网。官方 CLI 主动拒绝
`dsh web --host 0.0.0.0`（会把宿主机远程代码执行暴露到网络），
因此本插件让官方服务器保持只绑回环，另开监听并转发。

宿主端（index.js）
- 在 0.0.0.0:3082 监听，把 HTTP 与 WebSocket 转发到 127.0.0.1:<webServer 端口>
- 上游 Host/Origin 重写为回环，使官方 /api 信任围栏「通过」而不是被绕过
- 不改动 Set-Cookie：浏览器按请求 URL 建立 host-only cookie，转发层无需干预
- 监听端 DNS 重绑定防护；targetHost 仅接受回环地址（不会变成开放代理）
- /api/dsh-lan-access/summary 复用官方 connection.admit() 做围栏与浏览器认证
- 启动横幅打印带 launch token 的局域网链接
- 端口被占用时只告警不抛出，并在面板上报 listening:false，不展示不可用的二维码
- ownsHostCompat（默认关）：仅为非回环页面声明 ownsHost，恢复官方设置界面

客户端（src/ 经 scripts/build-client.mjs 生成 client.js）
- Settings → 局域网访问：局域网地址列表、复制/打开、选中地址的二维码
- 零依赖二维码编码器（byte 模式 / ECC M / version 1–10）

组合层
- 只 insert 一行，不覆盖任何 shipped row：停用本插件只会移除局域网监听，
  回环 Web UI 不受影响

验证
- 宿主转发契约 28/28；客户端契约 25/25
- 二维码编码器与 npm qrcode 参考实现在全版本 × 全 8 掩码下逐模块比对 240/240 一致
- 端到端：局域网 token 首访 303 并铸 cookie → 应用 200；无凭证 401；
  WebSocket 升级 101，且与直连回环逐项行为一致

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 sutong
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.