basic state switching from loading to running to editing

state/states/EditTrainState.ts

@@ -0,0 +1,25 @@
+import { State } from "../machine.ts";
+import { States } from "./index.ts";
+
+export class EditTrainState extends State<States> {
+  override name: States = States.EDIT_TRAIN;
+  override validTransitions: Set<States> = new Set([
+    States.RUNNING,
+    States.PAUSED,
+  ]);
+
+  override update(dt: number): void {
+    throw new Error("Method not implemented.");
+  }
+  override start(): void {
+    throw new Error("Method not implemented.");
+    // TODO
+    // Cache trains
+    // Stash train in context
+    // Draw track
+    // Draw train (filtered by train ID)
+  }
+  override stop(): void {
+    throw new Error("Method not implemented.");
+  }
+}