fix(xlsx): inset data bars from the row edges like Excel

[developer0hye]

Summary

• Inset XLSX conditional-format data bars from the row's top and bottom edges instead of filling the cell content height.
• Native Excel PDF exports of the business corpus print a 10 pt bar in every 14 pt row, which is 2 pt of clearance per side.
• A floor keeps the bar visible in rows shorter than the inset.

Related issue

Fixes #418

Testing

• cargo test --workspace (1817 tests, all pass)
• cargo clippy --workspace --all-targets (clean)
• cargo fmt --check
• pdftocairo -svg on page 1 of both PDFs to read the rendered gradient geometry directly
• pdftoppm -r 150 plus matched-region crops of the On Hand column at 300% scale

First data bar transform on page 1 of 03_inventory_en:

Render	Transform	Bar height
Excel GT	matrix(36, 0, 0, 10, 326, 134)	10.000 pt
before	matrix(36.203705, 0, 0, 13.184054, 325.606174, 132.443447)	13.184 pt
after	matrix(34.85704, 0, 0, 9.188886, 325.606174, 134.441031)	9.189 pt

The height error moves from +31.8% to -8.1%, and the white gaps Excel leaves between consecutive bars are restored. The residual comes from the auto-height branch approximating the printed row track as 1.2em; these rows are content-driven because they contain a wrapping cell, so the calibrated 14 pt track is not available to the renderer.

Visual impact

• No rendered PDF change
• Rendered PDF change or visual evidence added
• Reason:

Visual audit

• Issue: XLSX: data bars render 31.8% taller than Excel #418
• Fixture: tests/golden_mocks/business/sources/xlsx/03_inventory_en.xlsx
• Page(s): 1
• Renderer and DPI: pdftoppm, 150 DPI
• Evidence mode: fix
• New follow-up issues found in this audit: None
• GT: assets/bugfixes/issue-418/gt.jpg
• Before: assets/bugfixes/issue-418/before.jpg
• After: assets/bugfixes/issue-418/after.jpg
• Compare: assets/bugfixes/issue-418/compare.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

Deviation audit

Check	Result
Page count/order	Matches GT: four pages in the same order
Element presence	Matches GT: every bar, value, and header cell is present
Position/size	Fixed: bars are 9.189 pt tall against Excel's 10.000 pt, down from 13.184 pt
Rotation/flip	No deviation observed
Fill	Matches GT: the 638EC6 gradient and its lightened stop are preserved
Stroke/border	Matches GT: the cell grid rules are present at matching positions
Text content	Matches GT
Font family/weight/style	Matches GT
Text color	Matches GT
Alignment	Matches GT
Line/paragraph spacing	Matches GT: the 14 pt row tracks are unchanged
Clipping/overflow	Fixed: bars no longer merge into neighboring rows

Checklist

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