Remove debug HTML and parsing scripts, and clean up related code

- Deleted `debug_html.py`, `debug_parse.py`, `debug_selectors.py`, `debug_selectors2.py`, `debug_site.py`, `test_comprehensive.py`, and `test_googer.py` as they are no longer needed.
- Simplified the `HttpClient` struct initialization in `http_client.rs`.
- Improved formatting in the GET request logging and headers setting in `http_client.rs`.
- Cleaned up the `build_region_params` function in `utils.rs` for better readability.

Author: CocoRoF