feat: add one-click startup scripts for project management

- Add start.sh/start.bat for one-click startup (backend + frontend)
- Add stop.sh/stop.bat for stopping all services
- Add restart.sh for restarting services
- Add status.sh for checking service status
- Add Makefile with convenient management commands
- Add comprehensive documentation (ONE_CLICK_START.md)
- Update README with one-click startup instructions

Features:
- Automatic environment checking (venv, node_modules)
- Process management with PID tracking
- Unified log management (logs/*.log)
- Health checking after startup
- Support for Linux, macOS, and Windows
- No more need for multiple terminal windows

Usage:
  ./start.sh      # Start all services
  ./stop.sh       # Stop all services
  ./status.sh     # Check service status
  ./restart.sh    # Restart services
  make start      # Alternative using Makefile

Benefits:
- One command instead of multiple terminals
- Automatic environment validation
- Centralized logging
- Process lifecycle management
- Developer-friendly output messages

start.bat

@@ -0,0 +1,66 @@
+@echo off
+REM ERP AI Assistant - Windows 启动脚本
+
+setlocal enabledelayedexpansion
+
+echo ========================================
+echo    ERP AI Assistant - 启动中...
+echo ========================================
+echo.
+
+REM 项目根目录
+set PROJECT_ROOT=%~dp0
+set BACKEND_DIR=%PROJECT_ROOT%backend
+set FRONTEND_DIR=%PROJECT_ROOT%frontend
+set LOGS_DIR=%PROJECT_ROOT%logs
+
+REM 创建日志目录
+if not exist "%LOGS_DIR%" mkdir "%LOGS_DIR%"
+
+REM 检查虚拟环境
+if not exist "%BACKEND_DIR%\venv" (
+    echo [错误] 后端虚拟环境不存在
+    echo 请先运行: cd backend ^&^& python -m venv venv ^&^& pip install -r requirements.txt
+    exit /b 1
+)
+
+REM 检查 node_modules
+if not exist "%FRONTEND_DIR%\node_modules" (
+    echo [错误] 前端依赖未安装
+    echo 请先运行: cd frontend ^&^& npm install
+    exit /b 1
+)
+
+REM 检查 .env 文件
+if not exist "%BACKEND_DIR%\.env" (
+    echo [警告] .env 文件不存在，使用 .env.example
+    copy "%BACKEND_DIR%\.env.example" "%BACKEND_DIR%\.env" > nul
+)
+
+echo 启动后端服务...
+cd /d "%BACKEND_DIR%"
+start "ERP AI Assistant - Backend" cmd /c "venv\Scripts\activate && python -m app.main"
+echo   后端地址: http://localhost:8000
+echo   API文档: http://localhost:8000/docs
+
+echo.
+echo 启动前端服务...
+cd /d "%FRONTEND_DIR%"
+start "ERP AI Assistant - Frontend" cmd /c "npm run dev"
+echo   前端地址: http://localhost:5173
+
+echo.
+echo ========================================
+echo    启动完成！
+echo ========================================
+echo.
+echo 前端地址: http://localhost:5173
+echo 后端地址: http://localhost:8000
+echo API文档: http://localhost:8000/docs
+echo.
+echo 提示: 后端和前端已在新窗口中启动
+echo       关闭窗口即可停止服务
+echo.
+
+cd /d "%PROJECT_ROOT%"
+pause