fix: read content controls in DOCXToDocument

[LindseyZ1205]

Related Issues

• fixes DOCXToDocument drops the paragraphs and tables inside block-level content controls (w:sdt) #13163

Proposed Changes:

DOCXToDocument._extract_elements only handled the direct w:p and w:tbl children of the document body. Block-level content controls (w:sdt) keep their paragraphs and tables in w:sdtContent, so their content was dropped without any warning. Word uses them for cover pages, tables of contents and template fields.

A new _block_elements helper lists the body's children and replaces each content control with the elements in its w:sdtContent, recursively, so nested content controls are expanded too. _extract_elements iterates this list, so paragraphs (including text boxes, page breaks and links) and tables inside a content control go through the existing handling, in reading order.

How did you test it?

• Added test_run_reads_text_inside_a_content_control (paragraphs, including a nested content control, in reading order) and test_run_reads_a_table_inside_a_content_control. Both fail on main and pass with this change.
• Renamed the test helper _docx_with_text_box to _docx_with_block, since it now also builds the content-control documents. The text box tests are unchanged.
• hatch run test:unit (full unit suite), hatch run fmt, hatch run test:types, and pre-commit on the changed files.

Notes for the reviewer

Word also stores the table of contents in a block-level content control, so its entries now appear in the converted text, as they do in the document. If you'd rather skip the table of contents (its w:sdtPr has a w:docPartGallery of "Table of Contents"), I can add that.

This PR was generated with an AI assistant (Claude Code), including finding the bug. I have reviewed the changes and run the relevant tests locally.

Checklist

• I have read the contributors guidelines and the code of conduct.
• I have updated the related issue with new insights and changes.
• I have added unit tests and updated the docstrings.
• I've used one of the conventional commit types for my PR title.
• I have documented my code.
• I have added a release note file.
• I have run pre-commit hooks and fixed any issue.

🤖 Generated with Claude Code

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Coverage report

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File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
haystack/components/converters
docx.py					258
Project Total

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