Context

Currently, krknctl displays a warning when a newer version is available:

📣📦 A newer version of krknctl is available.

However, users must manually download and install the new version.

Goal

Introduce a new CLI command:

krknctl upgrade

This command should:

• Check the latest release from GitHub
• Compare it with the current installed version
• Download the latest binary
• Replace the existing binary
• Confirm successful upgrade

Acceptance Criteria

• Command successfully upgrades the CLI binary
• Works across supported OS platforms
• Graceful handling when already on latest version
• Clear success/failure messages