refactor(initialization): 调整初始化流程并添加新功能

- 在 Git 克隆命令中添加了特定分支参数
- 在初始化界面添加了跳转到最后一部的按钮
- 调整了 Python 后端启动路径

frontend/electron/services/gitService.ts

@@ -249,7 +249,7 @@ export async function cloneBackend(
         })
       }
       await new Promise<void>((resolve, reject) => {
-        const proc = spawn(gitPath, ['clone', '--progress', '--verbose', repoUrl, tmpDir], {
+        const proc = spawn(gitPath, ['clone', '--progress', '--verbose','--branch', 'feature/refactor-backend', repoUrl, tmpDir], {
           stdio: 'pipe',
           env: gitEnv,
           cwd: appRoot,

frontend/electron/services/pythonService.ts

@@ -403,7 +403,7 @@ export async function installDependencies(appRoot: string, mirror = 'tsinghua'):
 export async function startBackend(appRoot: string): Promise<{ success: boolean; error?: string }> {
   try {
     const pythonPath = path.join(appRoot, 'environment', 'python', 'python.exe')
-    const backendPath = path.join(appRoot, 'backend')
+    const backendPath = path.join(appRoot)
     const mainPyPath = path.join(backendPath, 'app','main.py')
 
     // 检查文件是否存在