feat(scala): Scala.js browser platform, snake and pong pages, build-web.sh

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

scala/web/Main.scala

@@ -0,0 +1,16 @@
+package snake
+package web
+
+import scala.scalajs.js.Dynamic.global
+
+// Two programs, one runtime: build-web.sh picks the entry point with --main-class.
+
+private def canvas() = global.document.getElementById("game")
+
+/** scala/index.html: Snake. */
+object SnakeMain:
+  def main(args: Array[String]): Unit = Runtime.runApp(App.main, BrowserPlatform(canvas()))
+
+/** scala/pong.html: Pong (m11). */
+object PongMain:
+  def main(args: Array[String]): Unit = Runtime.runApp(pong.PongApp.pongMain, BrowserPlatform(canvas()))