Fix/toc part metadata

[ghedo44]

Closes #736

Fix MSFT 10-K TOC metadata mapping: propagate PART context from standalone TOC rows and support display-style section names so section.item/section.part are populated consistently.

[dgunning]

Review

The parse_section_name regex generalization is clean and correct. The _infer_part_from_row_context approach is right in principle — walking backward through <tr> siblings to find standalone PART headers is a solid way to handle this TOC pattern.

However, there's one issue that needs fixing before merge:

text_content() on <tr> concatenates all cells without spaces

The regex ^\s*PART\s+([IVX]+)\b uses \b (word boundary) after the roman numeral. Real TOC rows often have page numbers in adjacent cells:

<tr><td>PART I</td><td>3</td></tr>

text_content() → "PART I3". The \b between I and 3 won't match because both are \w characters. This would silently fail to detect the part header.

The test uses clean single-cell rows that don't exercise this case. A fix could be to check <td> cell text individually rather than the whole row's text_content(), or adjust the regex.

Minor notes

• The backward sibling search in _infer_part_from_row_context is unbounded (walks all previous siblings). Consider adding a limit for consistency with the upward traversal limit of 10 in the same method.
• Test anchors in test_toc_analyzer_part_context.py all point to #i1 — would be cleaner with distinct anchors per item.
• No integration test with the actual MSFT filing that motivated this. Worth verifying the fix works end-to-end on the real filing.

[ghedo44]

Thanks for the detailed review. All requested items are addressed in 850cf7d.

• Fixed PART detection for multi-cell TOC rows: Now checks each td/th cell individually instead of relying on tr text content, correctly handling cases like PART I | 3
• Added bounded backward sibling scan: The backward tr walk is now capped with a row limit to prevent unbounded traversal
• Removed duplicated part parsing logic: Introduced a shared part-context helper reused across both detection paths
• Cleaned test anchors and added missing coverage: Updated test HTML with distinct anchors per item, added a test for PART rows with page-number cells, and added end-to-end verification against the real MSFT 10-K fixture

[dgunning]

Thanks a lot for your changes. This PR is approved and will be included in the next release.

Dwight