feat(docx): add checkbox parsing support

[ceberam]

Description

This PR adds support for parsing checkboxes in docx documents. Text with checkboxes is now properly identified and labeled as CHECKBOX_SELECTED or CHECKBOX_UNSELECTED in the resulting DoclingDocument.

Changes

• Checkbox detection and parsing: Added methods to detect checkboxes in DOCX files using Word 2010+ XML elements (w14:checkbox)
• Automatic symbol removal: Checkbox symbols (☐, ☑, ☒, etc.) are automatically removed from text content
• Proper labeling: Text items with checkboxes are labeled with DocItemLabel.CHECKBOX_SELECTED or DocItemLabel.CHECKBOX_UNSELECTED
• Code quality improvements:
  • Fixed missing return statement in _get_paragraph_elements() (also fixes textbox test)
  • Refactored duplicate code in text element handling (~25 lines removed)
  • Added Google-style docstrings to all new methods
• Comprehensive tests: Added tests for checkbox detection in both paragraphs and table cells

Testing

• Test file: tests/data/docx/docx_checkboxes.docx (12 checkboxes: 8 selected, 4 unselected)
• Added test_checkbox_detection_and_parsing(): Verifies checkbox detection and proper labeling
• Added test_checkbox_labels_in_tables(): Verifies checkboxes in table cells
• All tests use the documents fixture for efficiency

Resolves #858

Checklist:

• Documentation has been updated, if necessary.
• Examples have been added, if necessary.
• Tests have been added, if necessary.

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[github-actions]

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[dosubot]

Related Documentation

1 document(s) may need updating based on files changed in this PR:

Docling

What are the detailed pipeline options and processing behaviors for PDF, DOCX, PPTX, and XLSX files in the Python SDK?

View Suggested Changes

@@ -110,6 +110,7 @@
         - **Inline equations**: Multiple equations within text-containing paragraphs are preserved as distinct formula items
     - Previously, multiple sibling equations in a single paragraph were concatenated into a single LaTeX string, but this has been fixed to maintain each equation as a separate document item
     - **Inline Equations in List Items**: Inline formulas appearing in list items (both bulleted and numbered) are correctly processed and preserved in markdown exports. When a list item contains inline equations, they are exported with LaTeX `$` delimiters alongside the surrounding text
+      - **Checkboxes**: Checkboxes in DOCX files using Word 2010+ XML elements (`w14:checkbox`) are detected and parsed. Text with checkboxes is labeled as `CHECKBOX_SELECTED` or `CHECKBOX_UNSELECTED` in the resulting DoclingDocument. Checkbox symbols (☐, ☑, ☒, etc.) are automatically removed from the text content
 - **Notes**: Header/footer are automatically detected as FURNITURE layer. CLI/Serve API exports only BODY. [Example](https://app.dosu.dev/097760a8-135e-4789-8234-90c8837d7f1c/documents/e596ee79-fc7f-43a4-90e2-74891e0cf12f).
 
 ---

[Accept] [Decline]

^{How did I do? Any feedback?}  

[codecov]

Codecov Report

❌ Patch coverage is 94.28571% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
docling/backend/msword_backend.py	94.28%	2 Missing ⚠️

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