feat(fsharp): m01-m06 util, model, rules, random, spawn, game, view with Expecto tests

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

fsharp/solutions/View.fs

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+/// m06 view: the picture is plain data (a list of shapes); drawing it is somebody else's job (m07).
+module Snake.View
+
+open Snake.Model
+
+/// A thing to draw.
+type Shape =
+    | Rect of x: int * y: int * w: int * h: int * color: string
+    | Text of x: int * y: int * text: string * color: string * size: int * align: string
+
+/// A picture: shapes drawn in order.
+type Scene = Shape list
+
+let CELL = 20
+
+let private text x y str size align = Text(x, y, str, "#ffffff", size, align)
+
+// One cell, inset by 1px so neighbouring segments show a gap.
+let private cell (p: Point) color =
+    Rect(p.X * CELL + 1, p.Y * CELL + 1, CELL - 2, CELL - 2, color)
+
+let private overlay (state: GameState) : Scene =
+    let cx = state.Width * CELL / 2
+    let cy = state.Height * CELL / 2
+    let banner title hint = [ text cx cy title 32 "center"; text cx (cy + 30) hint 16 "center" ]
+
+    match state.Status with
+    | Paused -> banner "Paused" "Press Space to resume"
+    | GameOver -> banner "Game Over" "Press R to restart"
+    | Won -> banner "You Win!" "Press R to restart"
+    | Playing -> []
+
+let view (state: GameState) : Scene =
+    [ Rect(0, 0, state.Width * CELL, state.Height * CELL, "#111111") ]
+    @ (state.Apple |> Option.map (fun a -> cell a "#e53935") |> Option.toList)
+    @ (state.Snake |> List.mapi (fun i p -> cell p (if i = 0 then "#7cb342" else "#43a047")))
+    @ [ text 6 18 $"Score: {state.Score}" 16 "left" ]
+    @ overlay state