Preserve percent-encoded octets in href paths

[Sonai124]

Summary

• preserve syntactically valid %HH octets in href paths without decoding them as UTF-8
• continue quoting raw Unicode, spaces, and literal or malformed percent signs
• add HTML converter regression coverage for non-UTF-8 paths and URL escaping compatibility

Fixes #2171

Testing

• test_html_converter.py: 6 passed on Python 3.10, 3.11, and 3.12
• full local/CI-equivalent package suite: 307 passed, 34 skipped, 1 Windows-incompatible URI test deselected
• repository pre-commit hook: passed