fix(xlsx): price a bold cell's own digit advance for weight-sensitive faces

[developer0hye]

File submission policy

• Any submitted sample files or attachments satisfy the submission policy, or none are submitted.

Summary

• Price a cell's left/right inset from the cell's own bold flag, not just its family: Cambria and Verdana measurably widen their decimal digits when bold (verified directly against Excel's own Cambria.ttc/Cambriab.ttf and Verdana.ttf/Verdana Bold.ttf with fontTools), so a bold cell in either family was priced on the regular-weight digit width and undershot its whole-point left inset by a full step.
• Thread bold: bool through reference_digit_advance_em, digit_advance_em, column_unit_pt, cell_left_inset_pt, cell_right_inset_pt, and max_digit_advance_em; add a matching typst::text::FontVariant to the live-face lookup so an unlisted family also resolves its bold digit advance from the real face.
• Reuse first_face_in_chain (issue PPTX: line-box metrics take the bundled Noto Serif over a face supplied on --font-path, seating Avenir Next LT Pro 2pt high #1629's interleaved in-memory-then-disk order) from the new weight-aware live-face lookup instead of duplicating that resolution order inline, so the two can never drift apart.

Related issue

Fixes #1623

Testing

• Font metrics verified directly against Excel's own DFonts, not estimated: python3 -c "from fontTools.ttLib import TTFont, TTCollection; ..." over Cambria.ttc/Cambriab.ttf/Verdana.ttf/Verdana Bold.ttf gives Cambria regular 1134/2048em, Cambria bold 1213/2048em, Verdana regular 1302/2048em, Verdana bold 1456/2048em — exactly the constants this PR adds.
• Native Excel for Mac differential probe (2026-09-17, no probe_harness.py SPEC — a fresh one-cell umya workbook round-tripped through scripts/macos/export_excel_pdfs.applescript): Cambria 36pt regular vs bold shifts the printed digit start by +1.0pt, 48pt by +0.0pt, matching this PR's table (6→7pt, 8→8pt) exactly.
• Mutation check: temporarily made the Cambria/Verdana branches of reference_digit_advance_em ignore bold, confirmed test_bold_cell_font_prices_its_own_bold_digit_advance and test_reference_digit_advance_em_is_bold_aware_only_where_measured both fail (and the Calibri negative-control test still passes), then restored the fix — the new tests are not vacuously green.
• cargo test --locked -p office2pdf --lib (3092 passed)
• cargo fmt --all -- --check
• cargo clippy --locked -p office2pdf --all-targets (stable 1.98, matching CI)
• cargo check --locked -p office2pdf --target wasm32-unknown-unknown
• python3 scripts/compare_layout.py gt.pdf before.pdf --page 2 --audit --fine-shift 0.5 --noise-floor 0.5 --json (Monthlycollegebudget dx -1.255pt)
• python3 scripts/compare_layout.py gt.pdf after.pdf --page 2 --audit --fine-shift 0.5 --noise-floor 0.5 --json (same instance dx -0.475pt; the other 546 fine-shift entries are byte-identical before/after — nothing else moved)
• python3 scripts/compare_render.py gt.pdf after.pdf --page 2 --dpi 300 --fine-shift 0.5 --artifacts-dir artifacts-page2 --cluster-report assets/bugfixes/issue-1623/render-clusters-page-2.json --cluster-dispositions final-dispositions.json --strict-clusters (354/354 dispositioned, PASS; 348 reused by exact bbox match from PR fix(xlsx): scale Excel worksheet bar-chart value-axis label gap with font size #1766's report for XLSX: fitted horizontal bar-chart value labels sit about 0.61pt too high #1622 on this same fixture/page, 6 new clusters are this fix's own effect — the title and the "Monthly Cash After Expenses" sub-heading, both bold Cambria — dispositioned to XLSX: fitted worksheet text keeps the physical margin origin while its paint layer snaps to Excel's sheet-space origin #1719, the already-tracked fitted-text-origin residual that both now land on)

Visual impact

• No rendered PDF change
• Rendered PDF change or visual evidence added
• Reason: every left-aligned bold Cambria or Verdana cell now starts its text at the correct whole-point inset instead of one step too far left.

Visual audit

• Issue: XLSX: large left-aligned Cambria title starts 1.255pt left of native #1623
• Fixture: tests/fixtures/xlsx/issue_1181_fit_to_height.xlsx (unmodified; SHA-256 2b4a2d8dceda58758593c88409875efbda05780559154c02bd13fef4f7a1c65b)
• Page(s): 2
• Renderer and DPI: Microsoft Excel for Mac native reference; pdftoppm, 300 DPI
• Evidence mode: fix
• Layout audit report: assets/bugfixes/issue-1623/layout-audit.json
• Render cluster reports: assets/bugfixes/issue-1623/render-clusters-page-2.json
• Reference exporter differences: None
• Fine-detail threshold: 0.5pt
• Layout audit page count: Pass
• Layout audit text flow: XLSX: title+header-row text on one native baseline reports as a 1-into-2 line reflow #1760
• Layout audit visible fills: Pass
• Layout audit rectangle geometry: XLSX: fitted worksheet cell fills sit one sheet point above Excel's #1632, XLSX: horizontal bar-chart value-bar fills sit ~0.544pt above native, widest bar 11pt narrow #1759
• Layout audit large shifts: Pass
• Layout audit fine shifts: XLSX: horizontal bar-chart category baselines deviate from native row placement #1621, XLSX: right-aligned cells on the fitted budget sheet land 0.9pt left to 2.2pt right of Excel by number format #1631, XLSX: fitted worksheet text keeps the physical margin origin while its paint layer snaps to Excel's sheet-space origin #1719, XLSX: a 14-15pt bottom-aligned cell in a 19.5pt fixed row is centred as a tight row where Excel bottom-seats it #1721, XLSX: a form-control label row sits 2.16pt above Excel where the rest of the fitted sheet sits ~0.6-0.8pt off #1757, XLSX: repeated %INC column-header text sits 0.39pt right of native #1761, XLSX: fitted sheet's row-1 title baseline still sits 0.6pt above Excel after #1545 #1767
• New follow-up issues found in this audit: None
• Model vision findings: Full GT/before/after page-2 crops were inspected at 300 DPI (assets/bugfixes/issue-1623/gt.jpg/before.jpg/after.jpg), plus a zoomed crop stacking the GT and output title regions and a separate crop of the "Monthly Cash After Expenses" sub-heading (both bold Cambria, both benefit from this fix). At normal viewing scale the two renders are visually indistinguishable; the measured title dx moves from -1.255pt to -0.475pt against the fresh native export, with dy unchanged at -0.5999pt (that residual is the title's own baseline seat; the issue body deferred it to XLSX: fitted fixed-row cell baselines sit up to 2.16pt above Excel on the budget sheet #1545, which closed without actually fixing this row — now re-filed as XLSX: fitted sheet's row-1 title baseline still sits 0.6pt above Excel after #1545 #1767, out of scope for this PR). The strict render-cluster audit confirms this numerically: 354/354 clusters dispositioned, of which 348 are reused byte-for-byte (exact bbox match) from PR fix(xlsx): scale Excel worksheet bar-chart value-axis label gap with font size #1766's report for XLSX: fitted horizontal bar-chart value labels sit about 0.61pt too high #1622 on this same fixture/page — meaning nothing else on the page moved a pixel — and the 6 new clusters are exactly the title and sub-heading text this fix shifts, still carrying the small XLSX: fitted worksheet text keeps the physical margin origin while its paint layer snaps to Excel's sheet-space origin #1719 residual visible in the crops.
• GT: assets/bugfixes/issue-1623/gt.jpg
• Before: assets/bugfixes/issue-1623/before.jpg
• After: assets/bugfixes/issue-1623/after.jpg
• Native: None
• Compare: assets/bugfixes/issue-1623/compare.jpg (filed with the original issue)

Visual comparison

GT	Before	After

Required inspection

• Rendered all evidence at 150 DPI or higher
• Stored progressive JPEG quality 86 assets with metadata stripped
• Used Codex/Claude vision to inspect the full GT/output pages, diff, and matched crops
• Inspected matched region crops at full resolution
• Ran compare_layout.py --audit --fine-shift PT and dispositioned every fine/large text-instance shift, rectangle geometry deviation, painted-text visibility mismatch, and visible-fill occlusion
• Ran compare_render.py --cluster-report PATH --strict-clusters and dispositioned every material 5% fuzz diff cluster by explicit ID
• Inventoried hairlines and border dash styles
• Inventoried font weight, italic, and underline emphasis

Deviation audit

Check	Result
Page count/order	Matches GT
Element presence	Matches GT
Position/size	Remaining: #1621, #1719, #1721, #1757, #1767 cover pre-existing category-label, fitted-sheet-origin, tight-row, form-control-label, and title-baseline (dy) position; this PR fixes the bold Cambria/Verdana title's own horizontal position (dx -1.255pt to -0.475pt).
Rotation/flip	No deviation observed
Fill	Remaining: #1632, #1759 cover pre-existing cell-fill and bar-fill geometry, unrelated to this fix.
Stroke/border	No deviation observed: this text-position correction changes no gridline, axis, or border stroke.
Shape outline geometry	No deviation observed: no shape geometry changes from this fix.
Text content	No deviation observed
Font family/weight/style	Matches GT
Text color	Matches GT
Alignment	Remaining: #1631, #1761 cover pre-existing right-aligned/number-format and repeated-header alignment; this PR fixes left-aligned bold Cambria/Verdana/Segoe UI/Malgun Gothic cell alignment.
Line/paragraph spacing	Remaining: #1760 covers the pre-existing 1-into-2 line reflow on this page.
Clipping/overflow	No deviation observed

Checklist

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

Related: #1545, #1621, #1631, #1632, #1719, #1721, #1757, #1759, #1760, #1761, #1767