[FEAT cloudctl] - Add doctor command to reset local state

[onuryilmaz]

User Story

As a cloudctl user, I want a single command to reset my local cloudctl state, so I can recover from broken auth or cache issues without manual cleanup.

Description

cloudctl doctor — interactive confirmation prompt, then: clears kubelogin cache via kubelogin clean, deletes XDG cache dir, deletes XDG config dir. Informational output printed for each step.

Acceptance Criteria

• Interactive confirmation prompt before any destructive action
• kubelogin cache cleared via kubelogin clean
• XDG cache directory deleted
• XDG config directory deleted
• Informational output printed for each step

Reference Issues

Epic: #70

[github-actions]

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