feat(enterprise): add a dedicated license status command

[xe-nvdk]

Context

Arc exposes configured license health through the public /health response. arcli preserves that block in ping -o json, and cluster status displays limited license information when clustering is enabled, but there is no direct way to inspect license state on every deployment.

Scope

Add arcli license status backed by the /health license block.

Display the fields Arc provides, including tier, status, source, expiry, and site-license state when present. Do not imply that a missing license block is an error: it means no license is configured.

License installation and key/file configuration remain server configuration and are outside this command.

Acceptance criteria

• Table and JSON output are supported
• Active, expired/invalid, configured-but-unlicensed, and absent states are distinct
• Expiry is rendered consistently in UTC
• No token is sent to the public health endpoint
• Typed client and command tests cover all response shapes
• README/help and release notes document the command