feat(fsharp): m09 input/app/runtime and m10 extensions with tests

Co-Authored-By: Claude Opus 5.5 <[email protected]>

fsharp/solutions/App.fs

@@ -0,0 +1,28 @@
+/// m09 app: the whole game wired together as values: streams of actions in, a stream of drawings out.
+module Snake.App
+
+open Snake.Model
+open Snake.IO
+open Snake.Stream
+
+let TICK_MS = 150L
+let FRAME_MS = 25L
+
+// Everything that can happen to the game: a Tick every TICK_MS, and an action for each bound key.
+let classicActions: Stream<Action> =
+    Stream.merge (Stream.interval TICK_MS |> Stream.map (fun _ -> Tick)) (Stream.keyDowns |> Stream.choose Input.keyToAction)
+
+// m10: a Frame every FRAME_MS instead of a Tick; the game itself decides (movesEvery) which frames take a step.
+let speedActions: Stream<Action> =
+    Stream.merge (Stream.interval FRAME_MS |> Stream.map (fun _ -> Frame)) (Stream.keyDowns |> Stream.choose Input.keyToAction)
+
+// Actions folded into game states. startWith puts the initial state first so it is drawn right away.
+let states (seed: uint32) (actions: Stream<Action>) : Stream<GameState> =
+    actions |> Stream.scan Game.update (Spawn.newGame seed) |> Stream.startWith (Spawn.newGame seed)
+
+let render (state: GameState) : IO<unit> = IO.drawScene (View.view state)
+
+// The whole program as a value: get a seed, then turn the stream of states into a stream of drawings.
+// Nothing runs here; Runtime interprets it.
+let main () : IO<Stream<IO<unit>>> =
+    IO.randomSeed () |> IO.map (fun seed -> states seed speedActions |> Stream.map render)