Added two test files prune.test and error.test

[tarunkumartiwary1]

Added two tests prune.test and error.test.
Fixes : #67

I will file seperate issues and create PR for remaining command tests.

test

all tests passes successfully.

[AnupamKumar-1]

@tarunkumartiwary1 Nice work on this. The tests are well isolated and cover the main behavior of both commands. I also checked the assertions against the current implementations in errors.ts, prune.ts, sqlite-store.ts, and time.ts, and everything lines up.

A few non-blocking things to consider:

• expect(output).toContain("2 error(s)") could be a little stricter, e.g. /\b2 error\(s\)/, to avoid accidentally matching "12 error(s)".
• --limit, --since, and --watch aren't covered yet. That's fine if they're planned for follow-up PRs.
• It might be worth adding a boundary case for prune where the timestamp is exactly at the cutoff, just to make the < vs <= behavior explicit.
• buildProgram() and seedEvents() are duplicated between the two test files. With more command tests coming, a shared helper could make sense, but I wouldn't block this PR on it.

Overall this looks good to me. No production changes and the added coverage is useful.

[AnupamKumar-1]

LGTM, with some feedback.