refactor: simplify to maintain only one latest full package per app

- Remove per-version full package storage
- Remove RegenerateDependentVersions logic
- Only generate full package for the latest version
- Simplify package_util.go

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

backend/internal/router/admin/versions.go

@@ -354,7 +354,6 @@ func handleCreateVersionGlobal(c *gin.Context) {
 				lastFullVersion.FullPackagePath,
 				req.FilePath,
 				req.ApplicationID,
-				userID,
 			)
 			if err != nil {
 				log.Printf("[ERROR] Failed to merge patch with full package: %v\n", err)
@@ -571,11 +570,6 @@ func handleBatchDeleteVersions(c *gin.Context) {
 		return
 	}
 
-	// 删除后重新生成依赖这些版本的后续版本
-	for _, id := range req.IDs {
-		RegenerateDependentVersions(id)
-	}
-
 	response.Success(c, nil)
 }