todo: one file per item, grouped by theme, with a generated index

TODO.md had reached 1050 lines and 72 open items across 28 sections, read mostly
on a phone. It is now a directory: todo/<theme>/<item>.md, one card per file, with
frontmatter carrying id, status, created date and order, and the prose body copied
across verbatim. TODO.md becomes a generated index (bun run todo:index).

Dates: where an item's prose stated one it is used; otherwise its old section's;
otherwise 2026-08-20, floored at the day before the split rather than invented.
date_source records which.

Shaped for a two-way Kanban board, filed as todo/tooling — a card is a file, id is
the identity, frontmatter is the machine's half and the body is the owner's.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

todo/prompt-library/_index.md

@@ -0,0 +1,5 @@
+---
+theme: prompt-library
+heading: "Prompt library"
+kind: theme
+---

todo/prompt-library/a-store-of-ready-made-prompts-versioned.md

@@ -0,0 +1,22 @@
+---
+id: prompt-library/a-store-of-ready-made-prompts-versioned
+title: "A store of ready-made prompts, versioned, categorized and tagged"
+theme: prompt-library
+status: open
+created: 2026-08-21
+date_source: stated
+order: 1
+---
+
+**A store of ready-made prompts, versioned, categorized and tagged.** Wanted 2026-08-21. The owner
+keeps prompts he reuses; today they live nowhere. What it needs:
+- **Database rows** with the usual fields (`createdAt`, `modifiedAt`, …), one **category** each and
+  **multiple tags** per prompt.
+- **Versioning by row, not update-in-place.** Editing a prompt inserts a new row with a bumped
+  version. The UI shows the latest version unless asked otherwise, with copy-to-use as the primary
+  action.
+- **Categories do double duty:** they catalogue, and they decide where a prompt appears (or does
+  not) in the workspace/page-layout routing system.
+- **Open question, deliberately deferred:** a separate `kind` alongside `category` — e.g.
+  background-job prompt, image-generation prompt. Unclear whether both fields earn their keep;
+  keep both in the design and decide when building.