Add Windows installation scripts

- Add install.ps1 (PowerShell one-liner)
- Add install.bat (Batch script for double-click)
- Update README.md with Windows instructions

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

install.bat

@@ -0,0 +1,69 @@
+@echo off
+REM Claude Code Skills 安装脚本 (Windows - 备用方案)
+REM 双击运行此文件安装 skills
+
+setlocal
+
+set REPO_URL=https://git.let5see.xyz/let5see/skills.git
+set TEMP_DIR=%TEMP%\skills-install-%RANDOM%
+set SKILLS_DIR=%USERPROFILE%\.claude\skills
+
+echo ========================================
+echo   Claude Code Skills 安装程序
+echo ========================================
+echo.
+
+REM 检查 git 是否安装
+echo [1/4] 检查 Git...
+git --version >nul 2>&1
+if errorlevel 1 (
+    echo   [错误] 未找到 Git，请先安装 Git:
+    echo   https://git-scm.com/download/win
+    echo.
+    pause
+    exit /b 1
+)
+echo   Git 已安装
+echo.
+
+REM 创建临时目录并克隆仓库
+echo [2/4] 下载 skills...
+mkdir "%TEMP_DIR%" 2>nul
+git clone "%REPO_URL%" "%TEMP_DIR%" --depth 1 -q
+if errorlevel 1 (
+    echo   [错误] 下载失败
+    pause
+    exit /b 1
+)
+echo   下载完成
+echo.
+
+REM 创建 skills 目录
+echo [3/4] 安装 skills...
+if not exist "%SKILLS_DIR%" mkdir "%SKILLS_DIR%"
+
+REM 复制所有包含 SKILL.md 的目录
+set count=0
+for /d %%d in ("%TEMP_DIR%\*") do (
+    if exist "%%d\SKILL.md" (
+        echo   安装 %%~nxd
+        xcopy /E /I /Y "%%d" "%SKILLS_DIR%\%%~nxd\" >nul
+        set /a count+=1
+    )
+)
+echo   安装完成 (!count! 个 skills)
+echo.
+
+REM 清理临时文件
+echo [4/4] 清理临时文件...
+rmdir /S /Q "%TEMP_DIR%"
+echo   清理完成
+echo.
+
+echo ========================================
+echo   安装成功！已安装 !count! 个 skills
+echo ========================================
+echo.
+echo 提示: 重启 Claude Code 以加载新的 skills
+echo.
+pause