feat: add WeChat QR code login to config-server

Add in-app WeChat scanning via Tencent iLink API:
- server.js: QR code PNG renderer, WeChat API proxy, plugin auto-install
- index.html: WeChat channel card with QR display and polling UI
- Windows-Start.bat: auto-install WeChat plugin on startup
- Windows-Install.bat: copy WeChat plugin during installation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

portable/Windows-Install.bat

@@ -139,6 +139,16 @@ if "!USE_OPENCLAW!"=="usb" (
     echo   OpenClaw 下载安装完成!
 )
 
+REM ---- Copy extensions (WeChat plugin etc.) ----
+if exist "%APP_DIR%\extensions\openclaw-weixin\openclaw.plugin.json" (
+    echo   Installing WeChat plugin...
+    xcopy /s /e /q /y "%APP_DIR%\extensions\openclaw-weixin" "%INSTALL_TARGET%\extensions\openclaw-weixin\" >nul
+    REM Also install to ~/.openclaw/extensions/ for Gateway
+    mkdir "%USERPROFILE%\.openclaw\extensions" 2>nul
+    xcopy /s /e /q /y "%APP_DIR%\extensions\openclaw-weixin" "%USERPROFILE%\.openclaw\extensions\openclaw-weixin\" >nul
+    echo   WeChat plugin installed!
+)
+
 REM ---- Default config ----
 if not exist "%INSTALL_TARGET%\data\.openclaw\openclaw.json" (
     echo {"gateway":{"mode":"local","auth":{"token":"uclaw"}}} > "%INSTALL_TARGET%\data\.openclaw\openclaw.json"