feat(course): audit fixes and twelve extensions (Modules 7b, 12, 13)

Audit pass:
- Frame rule counts frames since the last move, so every step lasts
  exactly movesEvery(score) frames, also right after a speed-up
- clampTime + MAX_GAP_MS: a hidden tab no longer replays the whole gap
- Pong Restart keeps held keys
- Fact corrections (mulberry32 output coverage, Haskell IO, uniform)
- New fixture cases from a mutation analysis

Extensions (all three tracks, shared fixtures, course text):
- Turn queue (Exercise 10.6), persisted high score (10.7),
  replay viewer (10.8), play() end-to-end helper (9.5)
- Optional State (4.7) and optional Module 7b, stack-safe IO
- Module 12, property-based testing with generators, shrinking,
  invariants and a model-based oracle
- Module 13, Conway's Life with a Click event
- JS type checking via jsconfig, JSDoc and types.d.ts
- Maintainer tools: scripts/mutate.mjs, scripts/typecheck-js.sh,
  Playwright end-to-end suite (e2e/, scripts/e2e.sh)

Docs: docs/contract.md is the canonical contract; specs and build log
under docs/superpowers.

Verified: JS 728, Scala 689, F# 691 unit tests; stubs and progression
M01-M13 and M07b; 176 end-to-end tests on Chromium and WebKit.

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

js/solutions/pong/view.js

@@ -1,7 +1,10 @@
 // m11 pong view: the same Scene shapes as the snake view, so the same drawScene and runtime draw it.
 import { PCELL, PADDLE, PLAYER_X, CPU_X } from './model.js'
+/** @import { PongState, Scene, Shape } from '../types' */
 
+/** @type {(x: number, y: number, w: number, h: number, color: string) => Shape} */
 const rect = (x, y, w, h, color) => ({ tag: 'Rect', x, y, w, h, color })
+/** @type {(x: number, y: number, str: string, size: number) => Shape} */
 const text = (x, y, str, size) => ({ tag: 'Text', x, y, text: str, color: '#ffffff', size, align: 'center' })
 
 const paddle = (column, y) => rect(column * PCELL, y * PCELL, PCELL, PADDLE * PCELL, '#ffffff')
@@ -14,6 +17,7 @@ const overlay = (state) =>
     ]
     : []
 
+/** @type {(state: PongState) => Scene} */
 export const pongView = (state) => [
   rect(0, 0, 640, 400, '#111111'),
   paddle(PLAYER_X, state.player),