DOCX: preserve positioned footer tabs and borders

[developer0hye]

Problem

DOCX footer paragraphs can lose positioned tab-stop alignment, paragraph borders, and frame positioning, producing a visibly different footer from Microsoft Word.

Candidate public fixtures

• libreoffice/tdf159207_footerFramePrBorder.docx
• libreoffice/tdf156078_rightTabOutsideParaRightIndent.docx
• FancyFoot.docx

Acceptance criteria

• Select a minimal real-world fixture and export Microsoft Word PDF ground truth.
• Preserve footer tab-stop alignment and the affected paragraph border/frame positioning.
• Keep footer text and dynamic page fields intact.
• Add strict structural regression assertions for the relevant footer properties.
• Commit matched Word GT, Before, and After JPEGs under assets/bugfixes/issue-204/.
• Implement the fix in one focused PR using native Rust and TDD.

Related: #195

[developer0hye]

Fixed in #210 (0d7e5834b3f383312f8ade9238db6fac173140a7).

The DOCX pipeline now preserves positioned footer tabs, compound paragraph borders, footer edge distance, and page-anchored footer frames. The required paragraph-border reader support was also proposed upstream in bokuweb/docx-rs#897.

Microsoft Word GT	Before	After

Verification passed on macOS, Ubuntu, Windows, stable/MSRV, Clippy, formatting, WASM, and the bulk third-party fixture suite.