Select seed input after opening overlay

Fixes #93.

src/main/js/Game.ts

@@ -172,6 +172,7 @@ export class Game {
                 this.seedOverlay.show();
                 this.seedInput.value = this.seed;
                 this.seedInput.focus();
+                setTimeout(() => this.seedInput.select(), 0);
             }
         );
         this.seedOverlay = new Overlay(