Function render_note 

pub fn render_note(ex: &Explanation, source_base: Option<&str>) -> VaultNote

Render a node’s Explanation into an Obsidian note: YAML frontmatter (with tags for the graph view and an ADR’s status), a clickable Source link (when source_base — a web “blob” base like https://github.com/org/repo/blob/<sha> — is known and the node has a path), the captured content as the knowledge base, and its edges as provenance- labelled wikilinks.