fix(docx): seat bottom-anchored footer text

[developer0hye]

Summary

• Seat the DOCX footer WPS text box sits 8pt too low #1370 page-bottom WPS footer text one final-line em above its declared bottom inset, matching the supplied reference.
• Derive that em from the last measurable paragraph, including the renderer's 11pt default, instead of hard-coding the 8pt reference case.
• Add an end-to-end PDF baseline regression at both 8pt and 12pt plus fresh two-page visual evidence.

Related issue

Fixes #1370

Testing

• TDD red: CARGO_TARGET_DIR=/Volumes/T7/targets/office2pdf-issue-1370 cargo test -p office2pdf --lib a_bottom_seated_anchored_frame_keeps_one_em_above_its_bottom_inset -- --nocapture failed before the implementation: bottom-seated 8pt baseline 826.89pt should be 818.89pt.
• CARGO_TARGET_DIR=/Volumes/T7/targets/office2pdf-issue-1370 cargo test -p office2pdf --lib a_bottom_seated_anchored_frame_keeps_one_em_above_its_bottom_inset -- --nocapture (1 passed; 8pt, 12pt, and unstated/11pt-default PDF probes)
• CARGO_TARGET_DIR=/Volumes/T7/targets/office2pdf-issue-1370 cargo test -p office2pdf --lib render::typst_gen::tests::page_misc_tests -- --nocapture (79 passed)
• CARGO_TARGET_DIR=/Volumes/T7/targets/office2pdf-issue-1370 cargo test -p office2pdf --lib parser::docx::sections::anchor_tests -- --nocapture
• CARGO_TARGET_DIR=/Volumes/T7/targets/office2pdf-issue-1370 cargo test --workspace
• python3 -m unittest discover -s scripts/tests (266 passed)
• cargo fmt --all -- --check
• git diff --check
• Reconverted the Place your event title here.docx #1219 attachment from the final source; the resulting PDF is byte-identical to the visually audited after PDF (8d9423e06d25bc27393d6fe484d3febcbbedc9ff71d72cd07b708bffe434b2d4).
• python3 scripts/compare_layout.py --json --audit gt.pdf after.pdf (expected nonzero; remaining findings dispositioned to DOCX missing-font selection changes table wrapping and placement across hosts #1409 and Harness: detect text occluded by clipped opaque shadings #1450)
• python3 scripts/compare_render.py --page 1 --dpi 300 --audit --lines --artifacts-dir ... gt.pdf after.pdf and page 2 equivalent (expected nonzero; remaining text shifts dispositioned to DOCX missing-font selection changes table wrapping and placement across hosts #1409)
• Documentation freshness audit: PASS

Visual impact

• No rendered PDF change
• Rendered PDF change or visual evidence added
• Reason: the visible page-2 footer baseline moves up by 8pt; the same page-1 text remains correctly occluded behind body artwork.

Visual audit

• Issue: DOCX footer WPS text box sits 8pt too low #1370
• Fixture: Issue Place your event title here.docx #1219 attachment Place your event title here.docx
• Page(s): 1-2
• Renderer and DPI: pdftoppm, 300 DPI inspection; stored progressive JPEG evidence at 150 DPI
• Evidence mode: fix
• Layout audit report: assets/bugfixes/issue-1370/layout-audit.json
• Layout audit page count: Pass
• Layout audit text flow: DOCX missing-font selection changes table wrapping and placement across hosts #1409, Harness: detect text occluded by clipped opaque shadings #1450
• Layout audit large shifts: DOCX missing-font selection changes table wrapping and placement across hosts #1409
• New follow-up issues found in this audit: Harness: detect text occluded by clipped opaque shadings #1450
• Model vision findings: Full-page renders, 5% pixel diffs, and matched 300 DPI crops show the page-2 footer moved from 8.05pt too low to within 0.05pt of the GT baseline. Page 1 still visually occludes Sensitivity: Internal behind the body artwork, while the PDF text layer preserves it. The rotated photo, orange diamond, dot fields, gradients, circle, triangles, and white rules retain their geometry, fill, stroke, and orientation. Remaining title/body family and weight differences, WELCOME wrapping, subtitle/gate/RSVP shifts, and related alignment differences are DOCX missing-font selection changes table wrapping and placement across hosts #1409. The layout harness's false painted classification for the correctly occluded page-1 footer is Harness: detect text occluded by clipped opaque shadings #1450.
• GT: assets/bugfixes/issue-1370/gt.jpg
• Before: assets/bugfixes/issue-1370/before.jpg
• After: assets/bugfixes/issue-1370/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
• 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 and dispositioned every large text-instance shift and painted-visibility mismatch
• 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: two pages in the same order, with the RSVP page second
Element presence	Remaining: #1409 tracks the missing/extra line segmentation; all source elements and both footer text-layer instances remain present
Position/size	Remaining: #1409 tracks title, subtitle, ALL, AGES, gate, and RSVP shifts; the page-2 footer baseline is fixed to within 0.05pt of GT
Rotation/flip	Matches GT: the rotated photo and transformed decorations keep their orientation
Fill	Matches GT: the blue/pink gradients and solid decorations remain present at high DPI
Stroke/border	Matches GT: the white circle/arc, three outlined triangles, and white rules retain their hairline strokes; there are no dashed stroke styles, and the dot fields are filled circles
Shape outline geometry	Matches GT: matched crops show the diamond, circle, triangles, polygon, photo boundaries, and three vertical bars unchanged
Text content	No deviation observed: all source text remains extractable, including the visually occluded page-1 footer
Font family/weight/style	Remaining: #1409 tracks host-dependent title and body font family/weight metrics; bold title and gate emphasis remain present, with no italic or underlined runs in the fixture
Text color	Matches GT: text remains black on both pages
Alignment	Remaining: #1409 tracks font-metric-driven body alignment; the footer's vertical seat is fixed
Line/paragraph spacing	Remaining: #1409 tracks title and WELCOME line grouping plus the measured text shifts
Clipping/overflow	Remaining: #1409 tracks the output's three-line WELCOME overflow versus GT's four-line wrap; #1450 tracks the audit harness's false visibility classification for the correctly occluded page-1 footer

Checklist

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