Provides `normalize_html(html: str) -> str`, normalizing insignificant HTML whitespace, attribute ordering, self-closing tags, and entity references for conformance comparison. Uses only Python standard-library modules. RESULT: SUCCESS FILES CHANGED: - parser/blocks.py - renderer/html.py - test_render_blocks.py SUMMARY: Implemented block rendering fixes for raw HTML, thematic breaks, loose lists, headings, and escaped/generated HTML markup. Added regression tests. All 28 project tests pass; each declared block-scope section passes independently. BLOCKERS: - Full suite remains non-green due pre-existing inline-scope failures and timeout outside this build block.