fix: 修复补丁包返回逻辑，download_url 应返回补丁包地址

- 当最新版本是补丁类型时，download_url 返回补丁包地址（FilePath）
- full_package_url 返回完整包地址作为备选
- 简化判断逻辑，不再根据客户端版本判断

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/internal/router/app/info.go

@@ -205,45 +205,25 @@ func handleAppCheckUpdate(c *gin.Context) {
 	var fullPackageHash string
 	var isPatchUpdate bool
 
+	// 保存完整包地址（如果有）
+	if latestVersion.FullPackagePath != "" {
+		fullPackageURL = latestVersion.FullPackagePath
+		fullPackageSize = latestVersion.FullPackageSize
+		fullPackageHash = latestVersion.FullPackageHash
+	}
+
 	if latestVersion.UpdateType == "patch" && latestVersion.BaseVersionID != nil {
 		// 最新版本是补丁类型
-		// 检查客户端版本是否是基础版本
-		if clientVersionRecord.ID == *latestVersion.BaseVersionID {
-			// 客户端是基础版本，可以下载补丁包
-			downloadURL = latestVersion.FilePath
-			downloadSize = latestVersion.FileSize
-			downloadHash = latestVersion.FileHash
-			isPatchUpdate = true
-		} else {
-			// 客户端不是基础版本，需要下载完整包
-			if latestVersion.FullPackagePath != "" {
-				downloadURL = latestVersion.FullPackagePath
-				downloadSize = latestVersion.FullPackageSize
-				downloadHash = latestVersion.FullPackageHash
-			} else {
-				// 没有完整包，使用补丁包（可能合并失败）
-				downloadURL = latestVersion.FilePath
-				downloadSize = latestVersion.FileSize
-				downloadHash = latestVersion.FileHash
-			}
-		}
-		// 保存完整包地址作为备选
-		if latestVersion.FullPackagePath != "" {
-			fullPackageURL = latestVersion.FullPackagePath
-			fullPackageSize = latestVersion.FullPackageSize
-			fullPackageHash = latestVersion.FullPackageHash
-		}
-	} else {
-		// 全量版本，直接使用文件路径
+		// download_url 返回补丁包地址，full_package_url 返回完整包地址
+		downloadURL = latestVersion.FilePath
+		downloadSize = latestVersion.FileSize
+		downloadHash = latestVersion.FileHash
+		isPatchUpdate = true
+	} else {
+		// 全量版本，download_url 返回文件路径
 		downloadURL = latestVersion.FilePath
 		downloadSize = latestVersion.FileSize
 		downloadHash = latestVersion.FileHash
-		// 全量版本的完整包就是自己
-		if latestVersion.FullPackagePath != "" {
-			fullPackageURL = latestVersion.FullPackagePath
-			fullPackageSize = latestVersion.FullPackageSize
-			fullPackageHash = latestVersion.FullPackageHash
-		}
 	}
 
 	// 自定义地址优先级最高（覆盖下载地址）