feat: return latest version when no version param provided

If client doesn't provide version parameter, return latest version info
instead of returning error

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/internal/router/app/info.go

@@ -87,12 +87,6 @@ func handleAppCheckUpdate(c *gin.Context) {
 		return
 	}
 
-	// 客户端必须提供版本号
-	if clientVersion == "" {
-		response.Error(c, 400, "请提供客户端版本号")
-		return
-	}
-
 	// 清理版本号：去除空格和前缀 v/V
 	cleanVersion := func(v string) string {
 		v = strings.TrimSpace(v)
@@ -100,6 +94,47 @@ func handleAppCheckUpdate(c *gin.Context) {
 		v = strings.TrimPrefix(v, "V")
 		return v
 	}
+
+	// 如果没有传入版本号，直接返回最新版本
+	if clientVersion == "" {
+		latestVersion := &allVersions[0]
+
+		// 构建文件列表
+		files := make([]map[string]interface{}, len(latestVersion.Files))
+		for i, f := range latestVersion.Files {
+			files[i] = map[string]interface{}{
+				"file_path":   f.FilePath,
+				"file_name":   f.FileName,
+				"file_size":   f.FileSize,
+				"file_hash":   f.FileHash,
+				"file_type":   f.FileType,
+				"is_required": f.IsRequired,
+			}
+		}
+
+		// 确定下载地址：优先使用自定义地址
+		downloadURL := latestVersion.FilePath
+		if latestVersion.CustomDownloadURL != "" {
+			downloadURL = latestVersion.CustomDownloadURL
+		}
+
+		response.Success(c, gin.H{
+			"has_update":      true,
+			"latest_version":  latestVersion.Version,
+			"download_url":    downloadURL,
+			"file_size":       latestVersion.FileSize,
+			"file_hash":       latestVersion.FileHash,
+			"entry_file":      latestVersion.EntryFile,
+			"update_notes":    latestVersion.Description,
+			"update_strategy": latestVersion.UpdateStrategy,
+			"update_type":     latestVersion.UpdateType,
+			"update_method":   latestVersion.UpdateMethod,
+			"changelog":       latestVersion.Changelog,
+			"files":           files,
+		})
+		return
+	}
+
 	clientVersionClean := cleanVersion(clientVersion)
 
 	// 找到客户端当前版本对应的版本记录