chore(storybook): discover core-ui stories

Storybook's `stories` glob was emptied when core-ui became an optional
scaffoldable package. With core-ui present in the repo, wire the glob
back so its six stories are discovered — the manual post-scaffold step
the `gen core-package ui` generator already documents.

apps/storybook/.storybook/main.ts

@@ -2,7 +2,7 @@ import type { StorybookConfig } from "@storybook/react-vite";
 
 const config: StorybookConfig = {
   framework: "@storybook/react-vite",
-  stories: [],
+  stories: ["../../../packages/core-ui/src/**/*.stories.@(ts|tsx)"],
   addons: ["@storybook/addon-essentials"],
   docs: {
     autodocs: "tag",