Atomize Zettel

After finished text work, identify concepts, people, places, and ideas worth atomic notes (Cards), link in existing cards, and suggest updates to cards where the new material casts new light on already-established ideas. [WHAT] Scan recently produced/edited text against `Cards/_index.md`. Return three lists: NEW CANDIDATES (concepts worth their own card), EXISTING TO LINK IN (cards that exist but aren't linked), EXISTING TO UPDATE (cards where the text adds something substantive). The user chooses per row. Closes "the loop" between writing and the knowledge graph. [WHEN] Use when: atomize, "suggest atomic notes", "link in cards", "update cards", after a finished chronic…