PR into master from dev/olga/markdown-it-async-patch

[OlgaRedozubova]

branch: dev/olga/markdown-it-async-patch

What's been changed:

• Added src/markdown/async-patch.ts to monkey-patch markdown-it with asynchronous APIs:
  • Introduces core.processAsync, block.parseAsync, and inline.parseAsync with time-slicing via sliceMs and setImmediate.
  • Allows long-running Markdown parsing to run cooperatively without blocking the Node.js event loop.
• Added src/markdown/md-inline-rule/core-inline-async.ts:
  • Implements coreInlineAsync, an async replacement for the custom coreInline rule used in mathpix-markdown-it.
  • All inline parsing paths (regular inline tokens, tabular cells, and LaTeX footnote tokens) now use await state.md.inline.parseAsync(...).
  • Preserves existing behavior for footnotes, labels, currentTag/envToInline, math attributes, and text size calculation while making execution non-blocking.
• Introduced markdownToHTMLAsync (async pipeline entrypoint):
  • Async counterpart to markdownToHTML, using the patched markdown-it instance and async core/inline processing.
  • Designed to handle very large Markdown documents without causing long event-loop stalls, while keeping the HTML output compatible with the existing pipeline.

TODO:

• Add test for markdownToHTMLAsync and markdownToHtmlPipelineSegmentsAsync