Features
- Render markdown document as zettel
- Print metadata in card's header
- List references in card's footer
- Find backlinks and list them in card's footer
- Convert relative links to absolute
- Insert zettel title as top heading if not done
- Override previous / next page to follow the sequence of Zettelkasten IDs
- Collect links by tag
- Code highlighting test — sample code blocks for verifying syntax highlighting in light/dark modes
- References and backlinks test — zettel with both sections for verifying icons and footer styling
- Note types and maturity badges — type/maturity frontmatter, card header badges, and validation checks