[Prod DB Integration] HTML to Markdown Conversion Utility

[Enniwhere]

Description:
Implement a utility function to convert article HTML content to Markdown format for RAG processing, preserving links and structure.

Acceptance criteria:

• Function html_to_markdown(html: str) -> str converts HTML to Markdown
• Preserves internal article links (e.g., )
• Preserves external links and basic formatting (bold, italic, lists, paragraphs)
• Strips unnecessary HTML attributes while maintaining semantic structure
• Handles edge cases: empty strings, malformed HTML, special characters
• Unit tests with sample article HTML from lex.dk JSON responses
• Lists
• Tables
• Special characters
• Text boxes
• LaTeX formulae

Technical details:
Use markdownify library for HTML→Markdown conversion

Design:
Optional details on design for context.