Editable PPTX export overlaps large English heading text in WPS

[open-design-crew]

Summary

Editable PPTX export can produce unreadable overlapping large English heading text when opened in WPS Office.

This was found while manually validating PR #5644. The CJK font fallback fix appears to work, but this layout issue is separate and should be tracked independently.

Current behavior

On the exported positioning deck, slide 3 shows the large English heading overlapping/compressing badly in WPS. The SUSTAINABLE MODERN part of the title is rendered on top of itself and becomes unreadable.

CJK text on the same deck appears stable after #5644, so this looks more like an editable PPTX layout / font metrics / text box sizing issue than a CJK typeface fallback issue.

Expected behavior

Editable PPTX export should preserve the visual layout closely enough that large headings remain readable in WPS, especially for title text.

Steps to reproduce

1. Export the Open Design positioning deck as editable PPTX.
2. Open the exported .pptx in WPS Office.
3. Navigate to slide 3.
4. Observe the large English heading area.

Notes

• Observed during fix(desktop): keep CJK typefaces intact in editable PPTX export #5644 manual validation.
• Slide 1 CJK title and body text looked stable in WPS, so fix(desktop): keep CJK typefaces intact in editable PPTX export #5644's target behavior appears to pass.
• Slide 3 exposes a separate layout problem in the editable PPTX output.
• Attached screenshots show the passing CJK case and the overlapping heading case; the exported PPTX is also attached for reproduction.

Why this matters

Editable PPTX is a handoff artifact. Even when font fallback is correct, overlapping title text makes the deck unusable for client or stakeholder delivery in WPS.

[open-design-crew]

Evidence attached from manual validation:

• First screenshot: CJK title/body appears stable in WPS after fix(desktop): keep CJK typefaces intact in editable PPTX export #5644.
• Second screenshot: large English heading overlaps/compresses in WPS on slide 3.

Note: the exported editable PPTX used for reproduction is available locally at /Users/mac/Desktop/open-design-positioning-deck.pptx, but odc rejected .pptx as an unsupported attachment type. Supported attachment types are png, jpeg, gif, webp, mp4, webm, mov, and pdf.

open-design-positioning-deck.pptx

[lefarcen]

Thanks for splitting this out from #5644 — the slide 3 repro is clear, and the fact that slide 1 CJK now looks stable helps narrow the scope.

This does look like a separate editable-PPTX layout bug rather than the CJK fallback path we just fixed. The export path in apps/desktop/src/main/deck-capture.ts already does a DOM-side stabilization pass for oversized single-line text before it hands slides to the vendored dom-to-pptx engine, so the next useful step here is to reproduce this exact heading case against that path and add coverage for the WPS text-box / line-height sizing behavior.

Keeping this open as the bug follow-up to #5644.