Remove the hard-coded `template != \"default\"` guard so that
the default reference docx template is loaded automatically
when no --reference-doc is explicitly provided.
- Add new subcommands: convert, preflight, server, templates, webpage
- Migrate config from bin/config.json to ~/.config/mytoolkit
- Fix expand_bookmarks to modify writer objects instead of reader
- Improve md_to_pdf with CJK bookmark support
- Update README and project metadata