Enhance reference handling and table formatting in Lua filters

- Improved reference generation in filter_1.lua to handle cases where brackets are split from the reference number.
- Added logic to ensure proper formatting of references in filter_2.lua, organizing them into two columns for better readability.
- Introduced html_to_md.lua and md_to_html.lua scripts for converting HTML to Markdown and vice versa, with enhanced table handling and class tagging.
- Updated preprocessing.py to refine style marking and added functionality for redefining tags based on paragraph styles.
- Created styles.css to define CSS styles for various classes used in the document, ensuring consistent formatting across different elements.