Add structural OMML handlers for remaining LaTeX macros

[chitwitgit]

Summary

Follow-up to md2docx#7.

PR md2docx#7 replaces the hand-maintained symbol map with KaTeX-generated tables (~567 symbols). That covers most macros where the fix is simply resolving a command to the right Unicode glyph (e.g. \wedge → ∧).

The port still had gaps: some common macros need more than symbol lookup. N-ary operators must emit m:nary, not a ∫/∏ character in a text run. Layout commands like \binom and \stackrel need delimiter and limit structures. Font wrappers should render their argument, not the macro name. A few KaTeX macro-only symbols (\quad, \ne, \cdots) were also missing from the generated overrides.

This PR adds explicit handlers for those cases (~115 lines on top of md2docx#7).

What changed

lib/src/index.ts (+~110 lines)

Category	Macros	OMML
N-ary operators	\prod, \int, \oint, \bigcup, \bigcap, \bigoplus, \bigotimes	m:nary
Layout	\binom{a}{b}	m:d (round brackets + fraction)
Layout	\stackrel{a}{b}	m:limLoc + MathLimitUpper
Accents	\overline, \widetilde	createMathAccentCharacter
Font/text	\mathrm, \mathit, \textbf, \textit, \underline, \overbrace, \underbrace	argument content only (no literal macro name)
Skip	\boxed, \boldsymbol	no literal fallback
Other	\newline	space (non-empty OMML)

\sum unchanged — already handled via MathSum.

lib/scripts/generate-katex-data.ts (+4 lines)

Codegen fixes for macro-only symbols missed by simple alias parsing:

• \quad, \qquad — fixed \\\\hskip regex for vendored KaTeX file
• \ne → ≠ (alias of \neq)
• \cdots → ⋯ (via \@cdots)

Regenerated katexMeta.ts: 21 → 25 KATEX_SYMBOL_OVERRIDES.

Test plan

• pnpm build passes in lib/
• pnpm test passes in lib/
• Spot-check in Word: \binom{n}{k}, \int_0^1, \stackrel{def}{=}, \mathrm{ABC}, \prod_{i=1}^n