chore(storybook): localize sidebar menus and hide unused stories

src/patterns/loading-screen.stories.tsx

@@ -22,7 +22,8 @@ function Fullscreen() {
   )
 }
 
-const meta = { title: "Patterns/Layout/Loading Screen", parameters: { layout: "padded", controls: { disable: true } } } satisfies Meta
+// `internal` keeps it out of the sidebar by default; Story IDs and direct URLs stay valid.
+const meta = { title: "Patterns/Layout/Loading Screen", tags: ["internal"], parameters: { layout: "padded", controls: { disable: true } } } satisfies Meta
 export default meta
 type Story = StoryObj<typeof meta>