Add an --ignore CLI flag to skip specific packages

Sometimes a developer might have an internal private package that accidentally triggers the "Typosquat" or "Freshness" warnings. Instead of requiring a full configuration file, we should allow them to pass a quick inline flag to ignore certain packages.

**Example usage:**

`npx @dhanushnehru/lockcheck --ignore my-internal-lib,weird-name-pkg`

**Acceptance Criteria:**
-
- Parse the `--ignore` string in `bin/lockcheck.js` and split it by commas.
- Pass the array of ignored package names down into the `scan()` options.
- Filter out any findings in `src/index.js` where `finding.name` matches the ignored list before calculating the final exit code.

Start in bin/lockcheck.js by tracing how CLI options are parsed, then follow the options into scan() and inspect src/index.js where findings are evaluated for the final exit code. Verify the example command with comma-separated package names and confirm matching findings no longer affect the exit status.

Written by the indexing model from the issue text.