fix: [sc-139428] binary-version-reader` CLI output is not valid JSON

[monkbroc]

Story details: https://app.shortcut.com/particle/story/139428

Make the output of npx binary-version-reader usable as JSON.

[Copilot]

Pull request overview

Updates the binary-version-reader command-line interface to emit machine-consumable JSON so its output can be reliably piped into tools like jq.

Changes:

• Added a CLI-focused unit test that validates JSON output and error behavior.
• Updated cli.js to print JSON.stringify() output (and omit fileBuffer) instead of console.dir().
• Refreshed README CLI documentation and example output to reflect JSON output.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
specs/lib/cli.spec.js	Adds tests asserting the CLI returns parseable JSON and proper exit code on missing file.
cli.js	Switches CLI output to structured JSON and adds error handling.
README.md	Documents JSON CLI output and shows piping to jq.

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