Fix Linting and TypeScript Issues on a PR

Checks out a PR, auto-fixes linting and TypeScript issues, and pushes the fixes.

Step 1 — Get the PR number

If the user provided a PR number, use it directly. Otherwise ask for it.

Step 2 — Check out the PR

Use gh pr checkout so it works for both fork and non-fork PRs:

gh pr checkout <PR_NUMBER>

This automatically sets up the correct remote tracking and switches to the PR branch, even when the PR comes from a fork.

Step 3 — Install dependencies