refactor(painters/dom): unify textbox shape rendering (SD-2838)

[luccas-harbour]

Summary

Continues the SD-2838 effort to unify rendering paths in painters/dom. This branch consolidates the two pre-existing textbox text renderers — the WordArt SVG path and the HTML fallback path — into a single shared module so vector shapes, shape groups, and table-cell shapes all go through one code path.

• New module textbox/renderTextboxContent.ts centralizes WordArt (SVG + <text>/<tspan>) and fallback HTML rendering for shape text. Both branches share line-break handling, field resolution (PAGE/NUMPAGES), hex-color validation, and formatting application.
• Drawing content path (drawings/renderDrawingContent.ts) now delegates to renderTextboxContent, dropping ~270 lines of duplicated WordArt/fallback logic.
• Legacy createTextElement in svg-utils.ts is removed; it was the older foreignObject-based renderer that diverged from the drawing path.
• WordArt watermark predicate moves out of renderDrawingFragment.ts into textbox/wordArtWatermark.ts as isWordArtTextboxWatermarkBlock, with its own focused tests. renderer.ts imports from the new module for the header-watermark suppression rule.

[linear-code]

SD-2838

[chatgpt-codex-connector]

💡 Codex Review

superdoc/packages/layout-engine/painters/dom/src/drawings/tableDrawingFrame.ts

Lines 60 to 61 in cc9f268

	const drawingContent =
	renderDrawingContent?.(block, { clipContainer: drawingInner }) ?? createDrawingPlaceholder(doc);

Keep image drawings on built-in table rendering path

This helper now routes every table drawing through renderDrawingContent, including drawingKind: 'image'. In the previous behavior, image drawings were rendered by the built-in image path (object-fit, clip-path, hyperlink handling) and the callback was only for non-image drawing kinds; callers that provide a callback for vector/group shapes can now unintentionally replace image drawings with custom placeholders or lose image-specific styling. Guard image drawings before invoking the callback so custom renderers don't break table images.

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[luccas-harbour]

💡 Codex Review

superdoc/packages/layout-engine/painters/dom/src/drawings/tableDrawingFrame.ts

Lines 60 to 61 in cc9f268

	const drawingContent =
	renderDrawingContent?.(block, { clipContainer: drawingInner }) ?? createDrawingPlaceholder(doc);

Keep image drawings on built-in table rendering path
This helper now routes every table drawing through renderDrawingContent, including drawingKind: 'image'. In the previous behavior, image drawings were rendered by the built-in image path (object-fit, clip-path, hyperlink handling) and the callback was only for non-image drawing kinds; callers that provide a callback for vector/group shapes can now unintentionally replace image drawings with custom placeholders or lose image-specific styling. Guard image drawings before invoking the callback so custom renderers don't break table images.

ℹ️ About Codex in GitHub

Fixed.