Fix: namestore directory regression - restore 'names' subdirectory in path

[yankay]

Description

fix: #4525

This PR addresses a critical regression in the namestore directory creation logic, ensuring that container names are stored in the correct subdirectory structure.

Problem

Starting with v2.0, the namestore directory has been incorrectly created as <DATAROOT>/<ADDRHASH>/<NAMESPACE> (e.g., /var/lib/nerdctl/1935db59/default/foo) instead of the intended <DATAROOT>/<ADDRHASH>/names/<NAMESPACE>. This was caused by commit bf89c08, where the "names" subdirectory was inadvertently omitted from the path.

Breaking Change Warning

This fix introduces a breaking change because existing containers will no longer be recognized in the corrected path. Affected users must:

• Migrate existing name data to the new path

Due to the breaking fix, this may not be included in a patch release.

[Copilot]

Pull Request Overview

This PR fixes a critical regression in the namestore directory creation logic by restoring the missing "names" subdirectory in the path structure. This ensures container names are stored in the correct location as intended.

• Adds the missing "names" subdirectory to the namestore path construction
• Introduces comprehensive tests to verify the correct directory path creation
• Restores the intended directory structure from <DATAROOT>/<ADDRHASH>/<NAMESPACE> to <DATAROOT>/<ADDRHASH>/names/<NAMESPACE>

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
pkg/namestore/namestore.go	Fixes the path construction by adding "names" subdirectory to filepath.Join call
pkg/namestore/namestore_test.go	Adds test coverage for namestore creation with validation of correct directory path

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[AkihiroSuda]

Thanks, will merge when approaching the v2.2 release