refactor: fix type errors and improve type safety in PDF logic

- Add proper type assertions for DOM element properties
- Remove unused md-to-pdf feature
- Fix type errors in various PDF manipulation functions
- Improve type safety for HTML element interactions

CONTRIBUTING.md

@@ -82,6 +82,7 @@ When submitting code contributions, please use our [pull request template](.gith
     ```
 
 6.  **Push and Submit a Pull Request**
+
     ```bash
     git push origin feature/my-new-feature
     ```