feat: migrate README parser to markdown-it-py and refresh website

Switch readme_parser.py from regex-based parsing to markdown-it-py for
more robust and maintainable Markdown AST traversal. Update build pipeline,
templates, styles, and JS to support the new parser output. Refresh GitHub
stars data and update tests to match new parser behavior.

Co-Authored-By: Claude <noreply@anthropic.com>

pyproject.toml

@@ -25,6 +25,7 @@ dev = [
 
 [tool.pytest.ini_options]
 testpaths = ["website/tests"]
+pythonpath = ["website"]
 
 [tool.ruff]
 line-length = 200