Upgrade Lit to 2.8 and add Shoelace styles (#206)

src/shoelace.js

@@ -0,0 +1 @@
+// Cherry-picked Shoelace components:

src/ui.ts

@@ -11,6 +11,7 @@ import { Replay } from "./replay";
 import { Sorter } from "./sorter";
 import { URLResources } from "./url-resources";
 import { Embed } from "./embed";
+import "./shoelace";
 
 export {
   ReplayWebApp,