refactor(story): Update storybook wrapper

`storybook` provides a `decorators` object to let
us wrap components rendered in `storybook` with
some HTML.

This change wraps every component in a centered
flex box which is a nicer UX than the top left.

It also adds `MemoryRouter` which is required to
merge #69.

.storybook/preview.js

@@ -1,11 +1,16 @@
+import { MemoryRouter } from 'react-router-dom';
 import Style from './style';
 
 export const decorators = [
   (Story) => (
-    <>
+    <MemoryRouter initialEntries={['/']}>
       <Style />
-      <Story />
-    </>
+      <div className="flex h-screen items-center justify-center">
+        <div>
+          <Story />
+        </div>
+      </div>
+    </MemoryRouter>
   ),
 ];