Fix volume.fsck -forcePurging -reallyDeleteFromVolume to fail fast on filer traversal errors (#8015)

* Add TraverseBfsWithContext and fix race conditions in error handling

- Add TraverseBfsWithContext function to support context cancellation
- Fix race condition in doTraverseBfsAndSaving using atomic.Bool and sync.Once
- Improve error handling with fail-fast behavior and proper error propagation
- Update command_volume_fsck to use error-returning saveFn callback
- Enhance error messages in readFilerFileIdFile with detailed context

* refactoring

* fix error format

* atomic

* filer_pb: make enqueue return void

* shell: simplify fs.meta.save error handling

* filer_pb: handle enqueue return value

* Revert "atomic"

This reverts commit 712648bc354b186d6654fdb8a46fd4848fdc4e00.

* shell: refine fs.meta.save logic

---------

Co-authored-by: Chris Lu <chris.lu@gmail.com>

weed/command/filer_meta_backup.go

@@ -157,26 +157,18 @@ func (metaBackup *FilerMetaBackupOptions) shouldInclude(fullpath string) bool {
 }
 
 func (metaBackup *FilerMetaBackupOptions) traverseMetadata() (err error) {
-	var saveErr error
-
-	traverseErr := filer_pb.TraverseBfs(metaBackup, util.FullPath(*metaBackup.filerDirectory), func(parentPath util.FullPath, entry *filer_pb.Entry) {
+	return filer_pb.TraverseBfs(context.Background(), metaBackup, util.FullPath(*metaBackup.filerDirectory), func(parentPath util.FullPath, entry *filer_pb.Entry) error {
 		fullpath := string(parentPath.Child(entry.Name))
 		if !metaBackup.shouldInclude(fullpath) {
-			return
+			return nil
 		}
 
 		println("+", fullpath)
 		if err := metaBackup.store.InsertEntry(context.Background(), filer.FromPbEntry(string(parentPath), entry)); err != nil {
-			saveErr = fmt.Errorf("insert entry error: %w\n", err)
-			return
+			return fmt.Errorf("insert entry error: %w", err)
 		}
-
+		return nil
 	})
-
-	if traverseErr != nil {
-		return fmt.Errorf("traverse: %w", traverseErr)
-	}
-	return saveErr
 }
 
 var (