fix(docx): render a paragraph's left and right indent

[developer0hye]

Summary

• render a paragraph's w:ind left and right indent as a block inset
• keep the shading and border on the inner block, where Word paints them: from the left indent to the right indent
• keep w:spacing on the outermost block so an indent cannot break gap collapsing

Related issue

Fixes #464

Details

w:pPr/w:ind reached the IR but only the list path ever read it, so every indented body paragraph started at the page margin. In the technical-manual golden mock the shaded command lines carry a 240-twip (12pt) indent and rendered 11.95pt left of Word, while every unindented line on the same page matched within 0.05pt.

Line left edge (xMin) on page 1:

Line	Word GT	before	after
$ cargo install office2pdf-cli	82.80	70.85	82.85
$ office2pdf --version	82.80	70.85	82.85
office2pdf 0.6.0	82.80	70.85	82.85
$ office2pdf report.docx	82.80	70.85	82.85
$ office2pdf *.xlsx --outdir ./pdfs/	82.80	70.85	82.85

Word paints w:shd from the indent, not from the margin. Sampling the shaded band of the first code block at 150 DPI: Word starts it at 81.6pt against a 70.8pt margin, office2pdf started it at 71.0pt and now starts it at 83.0pt. The fill therefore belongs to a block nested inside the inset.

Vertical drift over the business corpus is unchanged at 13.52pt mean absolute, so the indent costs nothing elsewhere.

Testing

• cargo fmt --all -- --check
• cargo test --workspace
• cargo clippy --workspace --all-targets --all-features
• python3 scripts/validate_business_golden_mocks.py
• pdftotext -bbox x-position comparison against all 10 Word-produced DOCX golden PDFs
• shaded-band pixel sampling at 150 DPI, matched region crops, and magick compare -metric AE -fuzz 5%

Visual impact

• No rendered PDF change
• Rendered PDF change or visual evidence added
• Reason: indented paragraphs and their shading now start at the indent.

Visual audit

• Issue: DOCX: paragraph w:ind w:left is dropped outside lists #464
• Fixture: tests/golden_mocks/business/sources/docx/05_technical_manual_en.docx
• Page(s): page 1 of the Word GT and of the office2pdf output
• Renderer and DPI: pdftoppm, 150 DPI
• Evidence mode: fix
• New follow-up issues found in this audit: None
• GT: assets/bugfixes/issue-464/gt.jpg
• Before: assets/bugfixes/issue-464/before.jpg
• After: assets/bugfixes/issue-464/after.jpg

Visual comparison

GT	Before	After

Required inspection

• Rendered all evidence at 150 DPI or higher
• Stored progressive JPEG quality 86 assets with metadata stripped
• Inspected matched region crops at full resolution
• Ran the 5% fuzz pixel-difference sweep
• Inventoried hairlines and border dash styles
• Inventoried font weight, italic, and underline emphasis

The 5% fuzz sweep against the size-normalized GT falls from 57,544 to 54,480 differing pixels, both measured against current main so the #463 list-spacing fix is in each. The residual clusters are font antialiasing. The page's only hairline is the header rule, which matches GT in position, width, and weight on the full-resolution crop; there are no dashed or dotted borders. Bold headings, the monospace runs, and the italic disclaimer all keep the same emphasis as GT.

Deviation audit

Check	Result
Page count/order	Matches GT - two pages in the same order
Element presence	Matches GT - every heading, paragraph, command line, and the exit-code table are present
Position/size	Fixed - every command line now matches Word's x position within 0.05pt, and no line on the page deviates by more than 1pt horizontally
Rotation/flip	No deviation observed - the fixture contains no rotated or flipped elements
Fill	Fixed - the F4F4F4 shading now starts at the indent, 83.0pt against Word's 81.6pt
Stroke/border	No deviation observed - the header rule matches GT and there are no other strokes
Text content	Matches GT - all strings on both pages are preserved
Font family/weight/style	Matches GT - Arial body, Courier New code, bold headings, and the italic disclaimer all match
Text color	Matches GT - the navy headings, grey header, and black body all match
Alignment	Matches GT - the justified body paragraphs and centered footer match
Line/paragraph spacing	Matches GT - the list-boundary gap this fixture used to overshoot was fixed by #463, which is now on main
Clipping/overflow	No deviation observed - no glyph is clipped and nothing overflows the text column

Checklist

• Commits include a Signed-off-by line
• PR scope contains one root cause
• Remaining visual deviations each reference an open issue