Preserve percent-encoded href octets

[mturac]

Summary

• Preserve existing percent-encoded octets in HTML href paths instead of decoding them as UTF-8 first.
• Continue escaping raw spaces and raw percent signs in href paths.
• Add coverage for the EUC-JP / Shift-JIS-style percent-encoded case from Preserve percent-encoded octets in hrefs to avoid UTF-8 replacement (EUC-JP / Shift-JIS) #2171.

Validation

• cd packages/markitdown && PYTHONPATH=src uv run --with pytest --with markdownify --with beautifulsoup4 --with requests --with magika --with charset-normalizer --with defusedxml python -m pytest tests/test_module_misc.py -q -k percent_encoded_href
• git diff --check -- packages/markitdown/src/markitdown/converters/_markdownify.py packages/markitdown/tests/test_module_misc.py
• python3 -m py_compile packages/markitdown/src/markitdown/converters/_markdownify.py packages/markitdown/tests/test_module_misc.py

Fixes #2171

[mturac]

Closing this to avoid splitting review on the same issue. #2173 is already open for #2171 and covers the same percent-encoded href path, so I will leave that as the active review path.