A tree-sitter-based major mode for editing Markdown files.  Works
on Emacs 29, 30, and 31.  Features include syntax highlighting for
headings, emphasis, code spans, links, block quotes, and fenced
code blocks with embedded language highlighting.

Requires tree-sitter grammars:
- tree-sitter-markdown v0.4.1+
- tree-sitter-markdown-inline v0.4.1+