test: add coverage for the config subcommand (show, set, unset)

[sonukapoor]

The task

src/cli/config-command.ts has no test coverage. It is 44 lines and implements the cve-lite config subcommands: showing the current configuration, setting a value, and unsetting one.

This one is a step up from the first-timers-only issues because the function writes to console.log, so the tests need to capture that rather than just assert a return value.

What to cover

• show with no configuration set prints "No configuration set." and the config file path
• show with a caCert configured prints the key and its value
• set with a valid certificate path stores it
• set with an invalid path surfaces the validation error from validateCaCertFile
• unset removes a previously stored value

Getting started

tests/cli/config.test.ts already tests the underlying config.ts module and shows how to redirect HOME to a temporary directory so the real user config is never touched. Follow that pattern; a test that writes to the developer's actual config file would be a bug in the test.

For the console output, use jest.spyOn(console, "log") and restore it afterwards.

Steps

1. Comment here to claim it.
2. Branch, for example test/config-command-coverage.
3. npm install, then npm test to confirm a clean start.
4. Add tests/cli/config-command.test.ts.
5. npm test must pass, and no test may leave files behind outside its temp directory.
6. Open a PR with Closes #NNN.

Please do not change the behaviour of config-command.ts itself. If you find a genuine bug while writing the tests, mention it here and we will treat it separately.