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>

scripts/check-progression.sh

@@ -3,7 +3,7 @@
 # Progression checkpoint: for each module N (that has tests in the track), build a temp copy where src/ holds the
 # reference solutions of modules <= N and the untouched student stubs for the rest, then run the tests of modules
 # M01..MN. All must pass: this proves a student who has finished module N has a green suite up to N, and that
-# no earlier solution secretly depends on a later one.
+# no earlier solution secretly depends on a later one. The optional module 07b sits between 07 and 08.
 set -uo pipefail
 track="${1:?usage: check-progression.sh <js|scala|fsharp>}"
 repo="$(cd "$(dirname "$0")/.." && pwd)"
@@ -15,36 +15,45 @@ files_for() {
     js:01)     echo "util.js todo.js" ;;
     js:02)     echo "model.js" ;;
     js:03)     echo "rules.js" ;;
-    js:04)     echo "random.js spawn.js" ;;
+    js:04)     echo "random.js spawn.js state.js" ;;
     js:05)     echo "game.js" ;;
     js:06)     echo "view.js" ;;
     js:07)     echo "io.js" ;;
+    js:07b)    echo "safeio.js" ;;  # optional module 7b
     js:08)     echo "stream.js" ;;
     js:09)     echo "input.js app.js runtime.js browser.js main.js" ;;
-    js:10)     echo "" ;;  # edits game/input/app, already included by m05/m09
+    js:10)     echo "replay.js" ;;  # also edits game/input/stream/app/io/runtime/browser, already included by m05-m09
     js:11)     echo "pong" ;;
+    js:12)     echo "check.js" ;;
+    js:13)     echo "life" ;;
     scala:01)  echo "Util.scala" ;;
     scala:02)  echo "Model.scala" ;;
     scala:03)  echo "Rules.scala" ;;
-    scala:04)  echo "Random.scala Spawn.scala" ;;
+    scala:04)  echo "Random.scala Spawn.scala State.scala" ;;
     scala:05)  echo "Game.scala" ;;
     scala:06)  echo "View.scala" ;;
     scala:07)  echo "IO.scala" ;;
+    scala:07b) echo "SafeIO.scala" ;;
     scala:08)  echo "Stream.scala" ;;
     scala:09)  echo "Input.scala App.scala Runtime.scala" ;;
-    scala:10)  echo "" ;;
+    scala:10)  echo "Replay.scala" ;;
     scala:11)  echo "pong" ;;
+    scala:12)  echo "Check.scala" ;;
+    scala:13)  echo "life" ;;
     fsharp:01) echo "Util.fs" ;;  # Snake.fsproj lists every file from the start and is identical in both trees
     fsharp:02) echo "Model.fs" ;;
     fsharp:03) echo "Rules.fs" ;;
-    fsharp:04) echo "Random.fs Spawn.fs" ;;
+    fsharp:04) echo "Random.fs Spawn.fs State.fs" ;;
     fsharp:05) echo "Game.fs" ;;
     fsharp:06) echo "View.fs" ;;
     fsharp:07) echo "IO.fs" ;;
+    fsharp:07b) echo "SafeIO.fs" ;;
     fsharp:08) echo "Stream.fs" ;;
     fsharp:09) echo "Input.fs App.fs Runtime.fs" ;;
-    fsharp:10) echo "" ;;
+    fsharp:10) echo "Replay.fs" ;;
     fsharp:11) echo "Pong" ;;
+    fsharp:12) echo "Check.fs" ;;
+    fsharp:13) echo "Life" ;;
     *) echo "" ;;
   esac
 }
@@ -56,23 +65,44 @@ case "$track" in
   *) echo "unknown track: $track" >&2; exit 2 ;;
 esac
 
+# Modules in course order. "07b" (optional) comes after 07: order is position in this list, not numeric value.
+modules="01 02 03 04 05 06 07 07b 08 09 10 11 12 13"
+
+# Scala's `./test.sh M07` (munit glob "*M07*") and F#'s (Expecto --filter-test-list, a substring) also select the
+# M07b tests, unlike JS's "m07-*" glob. Before module 07b is reached its tests must not run, so delete them from
+# the temp copy (and, for F#, their line in tests/Snake.Tests.fsproj; Expecto finds test lists by attribute).
+drop_tests() {
+  case "$track" in
+    scala)  rm -f "$tmp"/scala/test/M"$1"*.test.scala ;;
+    fsharp) for f in "$tmp"/fsharp/tests/M"$1"*.fs; do
+              [ -e "$f" ] || continue
+              rm -f "$f"; sed -i "/Include=\"$(basename "$f")\"/d" "$tmp/fsharp/tests/Snake.Tests.fsproj"
+            done ;;
+  esac
+}
+
 status=0
-for n in 01 02 03 04 05 06 07 08 09 10 11; do
+for n in $modules; do
   has "$n" || continue
   tmp="$(mktemp -d)"
   tar -C "$repo" --exclude=.git --exclude=node_modules --exclude=bin --exclude=obj \
       --exclude=.scala-build --exclude=.bsp --exclude=.superpowers -cf - . | tar -C "$tmp" -xf -
-  for m in 01 02 03 04 05 06 07 08 09 10 11; do
-    [ "$m" -le "$n" ] || break
+  reached=""; past=0
+  for m in $modules; do
+    if [ $past -eq 1 ]; then   # a later module: drop its tests if a reached module's tag is a prefix of its tag
+      for r in $reached; do [[ "$m" == "$r"?* ]] && drop_tests "$m"; done
+      continue
+    fi
     for f in $(files_for "$m"); do
       [ -e "$tmp/$track/solutions/$f" ] || continue   # module not (yet) present in this track
       rm -rf "$tmp/$track/src/$f"
       cp -r "$tmp/$track/solutions/$f" "$tmp/$track/src/$f"
     done
+    reached="$reached $m"
+    [ "$m" = "$n" ] && past=1
   done
   ok=1
-  for m in 01 02 03 04 05 06 07 08 09 10 11; do
-    [ "$m" -le "$n" ] || break
+  for m in $reached; do
     has "$m" || continue
     if ! out="$(cd "$tmp/$track" && ./test.sh "M$m" 2>&1)"; then
       echo "checkpoint M$n: FAIL (M$m tests fail with solutions up to M$n)"