refactor(wiki): migrate this repo's .wiki/ to canonical Karpathy layout

Stop being inconsistent with our own fixed project-bootstrap template.

- SUMMARY.md → index.md (catalog by type, with one-line hooks)
- source/*.md → concepts/*.md (with `git mv` so history is preserved)
- WORKFLOW.md removed (workflow lives in wiki-maintainer, not duplicated here)
- New: .wiki/CLAUDE.md (project schema, Karpathy gist URL pinned at top)
- New: log.md (append-only op log; backfilled with prior decisions)
- New: overview.md (single project intro page)
- New: raw/README.md (immutability note; replaces .gitkeep placeholder)
- Empty .gitkeep added to entities/, packages/, sources/
- Migrated pages got `type: concept` frontmatter

After this, wiki-maintainer reads .wiki/CLAUDE.md → index.md as it expects,
and the layout matches what newly-bootstrapped projects will look like.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.tasks/STATUS.md

@@ -3,6 +3,17 @@ _Updated: 2026-04-28_
 
 ## Done
 
+### Migrate this repo's `.wiki/` to canonical Karpathy layout
+- [x] `git mv` `.wiki/source/*.md` → `.wiki/concepts/` (rename detection preserves history)
+- [x] Add `type: concept` frontmatter to each migrated page
+- [x] Create `.wiki/CLAUDE.md` (schema, with Karpathy gist URL pinned at top)
+- [x] Create `.wiki/index.md` (replaces `SUMMARY.md`)
+- [x] Create `.wiki/log.md` with backfilled entries for prior decisions
+- [x] Create `.wiki/overview.md` (project intro page)
+- [x] Create `.wiki/raw/README.md` (replaces `.gitkeep` placeholder)
+- [x] Empty `.gitkeep` in `.wiki/entities/`, `packages/`, `sources/`
+- [x] Delete `.wiki/SUMMARY.md`, `.wiki/source/`, `.wiki/raw/.gitkeep`
+
 ### project-bootstrap: align wiki init with Karpathy canon
 - [x] Read Karpathy gist + `wiki-maintainer` SKILL.md — gap confirmed
 - [x] Rewrite Step 3: create `index.md`, `log.md`, `overview.md`, `.wiki/CLAUDE.md` schema, `raw/README.md`, empty `entities/ concepts/ packages/ sources/` with `.gitkeep`