Py-tldr

Changed
- Fix 404 response boolean evaluation.
- Rename `build` as `rebuild` in Makefile.

Added
- Better prompts against network conditions.
- `DEBUG` env for exception hook.
- Massive code refactor.

Added
- Add spinners for better user experience.

Removed
- Remove `Rich` since it's too heavy and not ideal for MarkDown rendering.

Changed
- Refactor `Formatter` to process&render page content.
- Encapsulate `secho` as info&warn functions.

Added
- Use `tox` for test integration.
- Use `black` for formatting.
- Use `tbump` for version bumping.

Changed
- Fix `importlib.metadata` import error.