Add loading state (#1027)

* add loading state

* update snapshots

* add border radius

* fix comment breaking build jsx

src/types.ts

@@ -10,6 +10,7 @@ export type FlooredNumber = number & { _brand: "FlooredNumber" };
 export type Point = Readonly<RoughPoint>;
 
 export type AppState = {
+  isLoading: boolean;
   draggingElement: ExcalidrawElement | null;
   resizingElement: ExcalidrawElement | null;
   multiElement: ExcalidrawLinearElement | null;