feat(initialization): 添加初始化页面和相关功能

- 新增初始化页面组件和路由
- 实现环境检查、Git下载、后端代码克隆等功能
- 添加下载服务和环境服务模块
- 更新类型定义，增加 Electron API 接口

frontend/electron/services/downloadService.ts

@@ -0,0 +1,58 @@
+import * as https from 'https'
+import * as fs from 'fs'
+import { BrowserWindow } from 'electron'
+
+let mainWindow: BrowserWindow | null = null
+
+export function setMainWindow(window: BrowserWindow) {
+  mainWindow = window
+}
+
+// 下载文件的通用函数
+export function downloadFile(url: string, outputPath: string): Promise<void> {
+  return new Promise((resolve, reject) => {
+    console.log(`开始下载文件: ${url}`)
+    console.log(`保存路径: ${outputPath}`)
+    
+    const file = fs.createWriteStream(outputPath)
+    
+    https.get(url, (response) => {
+      const totalSize = parseInt(response.headers['content-length'] || '0', 10)
+      let downloadedSize = 0
+
+      console.log(`文件大小: ${totalSize} bytes`)
+
+      response.pipe(file)
+
+      response.on('data', (chunk) => {
+        downloadedSize += chunk.length
+        const progress = Math.round((downloadedSize / totalSize) * 100)
+        
+        console.log(`下载进度: ${progress}% (${downloadedSize}/${totalSize})`)
+        
+        if (mainWindow) {
+          mainWindow.webContents.send('download-progress', {
+            progress,
+            status: 'downloading',
+            message: `下载中... ${progress}%`
+          })
+        }
+      })
+
+      file.on('finish', () => {
+        file.close()
+        console.log(`文件下载完成: ${outputPath}`)
+        resolve()
+      })
+
+      file.on('error', (err) => {
+        console.error(`文件写入错误: ${err.message}`)
+        fs.unlink(outputPath, () => {}) // 删除不完整的文件
+        reject(err)
+      })
+    }).on('error', (err) => {
+      console.error(`下载错误: ${err.message}`)
+      reject(err)
+    })
+  })
+}