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>

e2e/package-lock.json

@@ -0,0 +1,58 @@
+{
+  "name": "pure-snake-e2e",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "pure-snake-e2e",
+      "devDependencies": {
+        "@playwright/test": "1.65.0"
+      }
+    },
+    "node_modules/@playwright/test": {
+      "version": "1.65.0",
+      "resolved": "https://registry.npmjs.org/@playwright/test/-/test-1.65.0.tgz",
+      "integrity": "sha512-iGURLGuKDLakSEl7Pgfv8h7f+XLT+V861Wfhz0zlEl5nyFuKUopdkFBPKqTllTUp06aOwPuH8iuUEb3yp3MpbQ==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "dependencies": {
+        "playwright": "1.65.0"
+      },
+      "bin": {
+        "playwright": "cli.js"
+      },
+      "engines": {
+        "node": ">=20"
+      }
+    },
+    "node_modules/playwright": {
+      "version": "1.65.0",
+      "resolved": "https://registry.npmjs.org/playwright/-/playwright-1.65.0.tgz",
+      "integrity": "sha512-F3AMWcR44qMBt4kq+6Kb6mX7bjGXshktKFOPULd7reED6ZJWevjbNRqysP7q+AATE9kdPEZBibex1BYsvpVoeA==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "dependencies": {
+        "playwright-core": "1.65.0"
+      },
+      "bin": {
+        "playwright": "cli.js"
+      },
+      "engines": {
+        "node": ">=20"
+      }
+    },
+    "node_modules/playwright-core": {
+      "version": "1.65.0",
+      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.65.0.tgz",
+      "integrity": "sha512-vNSKgH6YqtN7cdT/L334zo0a+YwkrpicyrHJlWWPIm/Q+Nn2SWInil01oT0mbu96U4GgoRtCYQD9CzJQgju+lA==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "bin": {
+        "playwright-core": "cli.js"
+      },
+      "engines": {
+        "node": ">=20"
+      }
+    }
+  }
+}