chore: catch up Storybook preview, coverage, and story hygiene

Stories were throwing without AuthModal/CreateFlow providers, autodocs was a no-op, and several DS/create-flow screens had no stories.

stories/navigation/MenuItem.stories.js

@@ -1,4 +1,8 @@
 import MenuItem from "../../app/components/navigation/MenuItem";
+import {
+  MENU_ITEM_MODE_OPTIONS,
+  MENU_ITEM_SIZE_OPTIONS,
+} from "../../lib/propNormalization";
 
 export default {
   title: "Components/Navigation/MenuItem",
@@ -15,12 +19,12 @@ export default {
   argTypes: {
     mode: {
       control: { type: "select" },
-      options: ["default", "inverse"],
+      options: [...MENU_ITEM_MODE_OPTIONS],
       description: "The visual style mode of the menu item",
     },
     size: {
       control: { type: "select" },
-      options: ["X Small", "Small", "Medium", "Large", "X Large"],
+      options: [...MENU_ITEM_SIZE_OPTIONS],
       description: "The size of the menu item",
     },
     disabled: {