fix(converter): preserve theme rFonts on DOCX round-trip (SD-2894)

[tupizz]

Summary

• Extends the combineRunProperties font-slot dedup to cover all four <w:rFonts> script slots (was only ascii/asciiTheme), so a higher-priority style with hAnsiTheme / eastAsiaTheme / cstheme no longer leaves the lower-priority concrete name in place.
• Adds the same theme-aware merge to calculateInlineRunPropertiesPlugin so theme references survive the mark-driven recompute that runs after import.

Why

Customer fixture in SD-2894 had every body run mapped to <w:rFonts w:asciiTheme="majorBidi" w:hAnsiTheme="majorBidi" w:cstheme="majorBidi"/>. The cascade only knew how to drop target.ascii when source.asciiTheme was present — the other three slots fell through, so the merged run carried { ascii: "Arial", hAnsi: "Arial", cs: "Arial", asciiTheme: "majorBidi", hAnsiTheme: "majorBidi", cstheme: "majorBidi" }. Word treats the concrete value as an override that defeats per-script theme resolution: Latin body text mapped to majorBidi rendered as Calibri Light instead of the per-script font (Times New Roman for Hebrew/Arab).

A second loss happened in calculateInlineRunPropertiesPlugin on initial load — the plugin computes fontFamily from textStyle marks (which only carry concrete CSS names) and overrode runProperties.fontFamily with concrete-only values, dropping the theme references that the import had stored.

Test plan

• New integration test (sd-2894-theme-rfonts-roundtrip.test.js) that round-trips the customer fixture and asserts w:asciiTheme / w:hAnsiTheme / w:cstheme counts don't drop and that no source theme reference becomes a concrete font on export.
• Existing ooxml-rFonts-rstyle-linked-combos-roundtrip test still passes.
• Full pnpm test for super-editor (12 708 / 12 721 pass).
• @superdoc/style-engine cascade unit tests pass.
• Manual verification: re-exported customer fixture from the dev app, opened in Word. asciiTheme count: 65 → 65 (was 65 → ~25). No Calibri Light substitutions on body text. Per-script resolution intact.

Verified diffs on the customer fixture

File	input	before fix	after fix
w:asciiTheme in document.xml	65	25	65
w:hAnsiTheme in document.xml	65	25	65
w:cstheme in document.xml	65	25	65
w:ascii="Calibri Light" runs in document.xml	0	1 (concrete substitution)	0

[linear]

SD-2894

[codecov-commenter]

Codecov Report

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