chore: keep the fixture generator scripts and the replay-sample bot

scripts/fixtures/ holds the scripts that produced the 2026-11-11
fixtures, with a README on running them safely into a copy. Run in
order they reproduce the content of every fixture they touch.

Co-Authored-By: Claude Fable 5.2 <noreply@anthropic.com>

docs/HANDOFF.md

@@ -17,6 +17,7 @@ The course is complete and green. It teaches functional programming by building
 | `<track>/src`, `<track>/solutions`, tests | Stubs, finished code, tests, for `js`, `scala`, `fsharp`. Same file names in `src` and `solutions`. |
 | `fixtures/` | Shared JSON test cases, read by all three tracks. |
 | `e2e/`, `scripts/e2e.sh` | Playwright end-to-end tests (maintainers only; the tracks have no dependencies). |
+| `scripts/fixtures/` | The small scripts that generated the 2026-11-11 fixtures, the bot behind the replay sample, and a README saying how to use them safely. |
 | `scripts/` | `verify.sh`, `check-stubs.sh`, `check-progression.sh`, `typecheck-js.sh`, `mutate.mjs` (+ `mutate-allow.txt`), `smoke.mjs`, `check-links.mjs`, `serve.mjs`. |
 | `docs/contract.md` | **The canonical contract**: data shapes, every module's rules, constants, pinned values, fixture inventory, required checks. |
 | `docs/superpowers/specs/` | `2026-10-28-…-design.md` (original design), `2026-11-11-audit-pass.md`, `2026-11-11-course-extensions.md` (twelve items, with the rules every builder followed). |
@@ -43,7 +44,7 @@ Environment on the machine this was built on: Node 24; `scala-cli` at `~/.local/
 ## How a change is made here
 
 1. **Decide the behaviour** and write it into `docs/contract.md` (and a spec under `docs/superpowers/specs/` if it is more than a fix).
-2. **JavaScript first**: stub with its doc comment, solution, tests, fixtures (generated from the JS solution with a throwaway script, then read by hand), course text.
+2. **JavaScript first**: stub with its doc comment, solution, tests, fixtures (generated from the JS solution with a small script — see `scripts/fixtures/README.md` — then read by hand), course text.
 3. **Port to Scala and F#**, touching only that track's directory. Use the same seeds and run counts so pinned values match; if a pinned value differs, the draw order differs — find out why before changing a test.
 4. **Run every check above** for every track you touched, and the e2e suite for anything a page shows.
 5. **Record** what you decided in the build log.