fix(storybook): wire Tailwind v4 theme into Storybook preview

- Split globals.css into globals.css + theme.css so Storybook can
  import design tokens without the @import "tailwindcss" directive
  that breaks Vite's preview module loading
- Prepend @tailwindcss/vite plugin for correct processing order
- Add @source to scan core-ui components for utility class generation

apps/storybook/.storybook/main.ts

@@ -8,12 +8,9 @@ const config: StorybookConfig = {
     autodocs: "tag",
   },
   async viteFinal(config) {
-    const { mergeConfig } = await import("vite");
     const tailwindPlugin = await import("@tailwindcss/vite");
-
-    return mergeConfig(config, {
-      plugins: [tailwindPlugin.default()],
-    });
+    config.plugins = [tailwindPlugin.default(), ...(config.plugins || [])];
+    return config;
   },
 };