This adds functionality to automatically comment on PRs with link checker
results when the Mintlify deployment completes. The comment will be updated
on subsequent runs and clearly indicates whether all links are valid or if
issues were found.

- Fix JavaScript syntax error when exit_code is empty
- Handle both pull_request and deployment_status events properly
- Use safe string interpolation for exit code
- Fallback to docs.wandb.ai when no deployment URL available

Change push trigger to only run on main branch. This prevents duplicate
workflow runs when pushing to PR branches (which triggers both push and
pull_request events).

Now:
- PRs: validated via pull_request trigger
- Main branch: validated via push trigger
- Manual: workflow_dispatch still available

…omment