feat: auto-generate full package when uploading patch

- Add FullPackagePath, FullPackageSize, FullPackageHash to Version model
- When uploading patch, merge with base full package to create new full package
- Check update API returns full package info for download
- Add package_util.go with merge functions

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

backend/internal/router/admin/versions.go

@@ -336,11 +336,38 @@ func handleCreateVersionGlobal(c *gin.Context) {
 		version.UpdateMethod = "auto"
 	}
 
-	if version.UpdateType == "patch" {
+	// 处理全量包和补丁包
+	if version.UpdateType == "full" {
+		// 全量包：full_package 就是自己
+		version.FullPackagePath = version.FilePath
+		version.FullPackageSize = version.FileSize
+		version.FullPackageHash = version.FileHash
+	} else if version.UpdateType == "patch" {
+		// 补丁包：需要找到基础全量包并合并
 		var lastFullVersion model.Version
 		if err := database.DB.Where("application_id = ? AND update_type = ?", req.ApplicationID, "full").
 			Order("id DESC").First(&lastFullVersion).Error; err == nil {
 			version.BaseVersionID = &lastFullVersion.ID
+
+			// 合并生成新的全量包
+			fullPkgPath, fullPkgSize, fullPkgHash, err := MergePatchWithFullPackage(
+				lastFullVersion.FullPackagePath,
+				req.FilePath,
+				req.ApplicationID,
+				userID,
+			)
+			if err != nil {
+				log.Printf("[ERROR] Failed to merge patch with full package: %v\n", err)
+				response.Error(c, 500, "合并补丁包失败: "+err.Error())
+				return
+			}
+
+			version.FullPackagePath = fullPkgPath
+			version.FullPackageSize = fullPkgSize
+			version.FullPackageHash = fullPkgHash
+		} else {
+			response.Error(c, 400, "找不到基础全量包，无法创建补丁版本")
+			return
 		}
 	}