fix: honor --version without a command

[slegarraga]

Closes #4.

Moves the --version check ahead of the help branch so a bare version probe prints the version and exits 0. Adds CLI tests covering --version, no command, and --help.

Verified with npm run typecheck and npm test (50 passed).

[github-actions]

Welcome, @slegarraga, and thanks for your first pull request to MCP-audit.

A quick look at CONTRIBUTING.md covers how things are set up and run here.

I'll review this shortly. Ask anything in the thread if something is unclear.

[royalpinto007]

Closing this PR.

The author is no longer an active contributor on these repositories, so this cannot be carried through review or iterated on.

The underlying issue stays open and is available for anyone who wants it. If you were looking at this change, please do open a fresh PR, it is very welcome.