feat: 添加智能分支选择功能

在WebUI的插件安装中实现远程仓库分支自动检测功能，当main分支不存在时自动选择main或master分支。添加_get_available_branches方法获取远程分支列表，并在克隆失败时尝试智能切换分支。优化克隆过程中的分支选择和错误处理逻辑。

src/webui/git_mirror_service.py

@@ -555,12 +555,94 @@ class GitMirrorService:
 
         return await self._clone_with_url(url, target_path, branch, depth, mirror["id"])
 
+    async def _get_available_branches(self, url: str) -> List[str]:
+        """获取远程仓库的可用分支列表"""
+        try:
+            logger.info(f"正在获取远程分支列表: {url}")
+            
+            # 使用 git ls-remote 获取分支列表
+            cmd = ["git", "ls-remote", "--heads", url]
+            
+            loop = asyncio.get_event_loop()
+            
+            def run_git_ls_remote():
+                return subprocess.run(
+                    cmd,
+                    capture_output=True,
+                    text=True,
+                    timeout=60,  # 1分钟超时
+                )
+            
+            process = await loop.run_in_executor(None, run_git_ls_remote)
+            
+            if process.returncode == 0:
+                branches = []
+                for line in process.stdout.strip().split('\n'):
+                    if line:
+                        # 解析分支引用，格式: "<hash>\trefs/heads/<branch_name>"
+                        parts = line.split('\t')
+                        if len(parts) == 2 and parts[1].startswith('refs/heads/'):
+                            branch_name = parts[1].replace('refs/heads/', '')
+                            branches.append(branch_name)
+                
+                logger.info(f"获取到分支列表: {branches}")
+                return branches
+            else:
+                logger.warning(f"获取分支列表失败: {process.stderr}")
+                return []
+                
+        except subprocess.TimeoutExpired:
+            logger.warning("获取分支列表超时")
+            return []
+        except Exception as e:
+            logger.error(f"获取分支列表时发生错误: {e}")
+            return []
+
     async def _clone_with_url(
         self, url: str, target_path: Path, branch: Optional[str], depth: Optional[int], mirror_type: str
     ) -> Dict[str, Any]:
-        """使用指定 URL 克隆仓库，支持重试"""
+        """使用指定 URL 克隆仓库，支持重试和智能分支选择"""
         attempts = 0
         last_error = None
+        
+        # 初始分支选择
+        selected_branch = branch
+        branch_selection_tried = False  # 标记是否已经尝试过智能分支选择
+        
+        # 如果没有指定分支，或者指定了分支但后续发现不存在，则进行智能分支选择
+        if not selected_branch or branch:
+            logger.info(f"初始分支选择: {selected_branch or '未指定分支'}，开始检测可用分支...")
+            available_branches = await self._get_available_branches(url)
+            
+            if available_branches:
+                logger.info(f"检测到的分支: {available_branches}")
+                
+                # 如果指定了分支，先检查该分支是否存在
+                if branch and branch in available_branches:
+                    selected_branch = branch
+                    logger.info(f"指定的分支 '{branch}' 存在，使用该分支")
+                else:
+                    # 如果指定了分支但不存在，记录日志
+                    if branch and branch not in available_branches:
+                        logger.warning(f"指定的分支 '{branch}' 不存在，将进行智能分支选择")
+                    
+                    # 优先选择 main 分支
+                    if "main" in available_branches:
+                        selected_branch = "main"
+                        logger.info("选择 main 分支")
+                    # 其次选择 master 分支
+                    elif "master" in available_branches:
+                        selected_branch = "master"
+                        logger.info("选择 master 分支")
+                    # 如果都没有，使用默认分支（不指定分支参数）
+                    else:
+                        selected_branch = None
+                        logger.info("未找到 main 或 master 分支，使用默认分支")
+                        
+                branch_selection_tried = True
+            else:
+                logger.warning("无法获取分支列表，将使用默认分支或指定分支")
+                selected_branch = branch  # 保持原分支设置
 
         for attempt in range(self.max_retries):
             attempts += 1
@@ -575,8 +657,8 @@ class GitMirrorService:
                 cmd = ["git", "clone"]
 
                 # 添加分支参数
-                if branch:
+                if selected_branch:
-                    cmd.extend(["-b", branch])
+                    cmd.extend(["-b", selected_branch])
 
                 # 添加深度参数（浅克隆）
                 if depth:
@@ -590,10 +672,11 @@ class GitMirrorService:
                 # 推送进度
                 if _update_progress:
                     try:
+                        branch_info = f"分支: {selected_branch}" if selected_branch else "默认分支"
                         await _update_progress(
                             stage="loading",
                             progress=20 + attempt * 10,
-                            message=f"正在克隆仓库 (尝试 {attempt + 1}/{self.max_retries})...",
+                            message=f"正在克隆仓库 {branch_info} (尝试 {attempt + 1}/{self.max_retries})...",
                             operation="install",
                         )
                     except Exception as e:
@@ -620,11 +703,44 @@ class GitMirrorService:
                         "mirror_used": mirror_type,
                         "attempts": attempts,
                         "url": url,
-                        "branch": branch or "default",
+                        "branch": selected_branch or "default",
                     }
                 else:
-                    last_error = f"Git 克隆失败: {process.stderr}"
+                    error_output = process.stderr
+                    last_error = f"Git 克隆失败: {error_output}"
                     logger.warning(f"克隆失败 (尝试 {attempt + 1}/{self.max_retries}): {last_error}")
+                    
+                    # 如果是因为指定分支不存在导致的失败，尝试智能分支选择
+                    if (selected_branch and 
+                        ("Remote branch" in error_output and "not found" in error_output) and
+                        not branch_selection_tried):
+                        
+                        logger.info(f"分支 '{selected_branch}' 不存在，尝试智能分支选择...")
+                        
+                        # 重新检测分支
+                        available_branches = await self._get_available_branches(url)
+                        if available_branches:
+                            logger.info(f"可用分支: {available_branches}")
+                            
+                            # 优先选择 main 分支
+                            if "main" in available_branches:
+                                selected_branch = "main"
+                                logger.info("切换到 main 分支")
+                            # 其次选择 master 分支
+                            elif "master" in available_branches:
+                                selected_branch = "master"
+                                logger.info("切换到 master 分支")
+                            # 如果都没有，使用默认分支
+                            else:
+                                selected_branch = None
+                                logger.info("切换到默认分支")
+                                
+                            branch_selection_tried = True
+                            # 重置尝试计数，给新的分支选择一个完整的机会
+                            attempts = 0
+                            continue  # 重新开始循环
+                        else:
+                            logger.warning("无法获取分支列表，继续尝试下一个镜像源")
 
             except subprocess.TimeoutExpired:
                 last_error = "克隆超时（超过 5 分钟）"