[WIP] Address feedback on versioned key update support

[Copilot]

• Add JSDoc documentation for updatedAt property in StoredKeyMetadata interface
• Add JSDoc documentation for versions property in StoredKeyMetadata interface
• Validate changes with code review
• Run security checks

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[Copilot]

Pull request overview

This PR adds JSDoc documentation for two new optional properties in the StoredKeyMetadata interface to support versioned key update functionality. The changes enhance code documentation by describing the updatedAt timestamp and versions array properties that track key update history.

• Added JSDoc documentation for the updatedAt property describing the ISO 8601 timestamp of the last key update
• Added JSDoc documentation for the versions property describing the array of historical key versions

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