fix: ignore empty directories in device clean scan

[ssongliu]

Refs #13435

[Copilot]

Pull request overview

This PR updates the agent’s device cleanup scan logic to avoid surfacing empty directories by computing directory trees and sizes in a single recursive traversal, primarily for rollback/upload/download-related cleanup items.

Changes:

• Refactors rollback scan to no longer require fileOp and instead build rollback trees via the updated helper.
• Replaces loadTreeWithCheck’s size-gating (previously based on GetDirSize) with a new recursive walker that returns both a file tree and aggregated size.
• Introduces loadTreeWithFileSize to skip empty directories while building dto.CleanTree results.

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[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Suppressed comments (2)

agent/app/service/device_clean.go:869

• loadTreeWithFileSize currently skips any entry whose computed item.Size is 0, which also filters out 0-byte files. The PR title/intent is to ignore empty directories; silently hiding 0-byte files is an additional behavior change and may prevent users from cleaning placeholder/empty files inside otherwise non-empty trees.

		if item.Size == 0 {
			continue
		}

agent/app/service/device_clean.go:828

• loadTreeWithCheck now derives Size by summing os.DirEntry.Info().Size() via loadTreeWithFileSize, while most other scan sections use fileOp.GetDirSize() (which uses du and reflects disk usage). This makes the reported sizes inconsistent across cleanup categories and can under-report reclaimable space (e.g., filesystem blocks, sparse files), which may confuse users.

This issue also appears on line 867 of the same file.

func loadTreeWithCheck(treeData []dto.CleanTree, pathItem, treeType string) []dto.CleanTree {
	list, size := loadTreeWithFileSize(true, pathItem, treeType, pathItem)
	if len(list) == 0 || size == 0 {
		return treeData
	}
	treeData = append(treeData, dto.CleanTree{ID: uuid.NewString(), Label: treeType, Size: size, IsCheck: size > 0, Children: list, Type: treeType, IsRecommend: true, CanDelete: false})