chore: mark a few more imports as external to fix build warnings (#695)

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### ❓ Type of change

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- [ ] 📖 Documentation (updates to the documentation or readme)
- [ ] 🐞 Bug fix (a non-breaking change that fixes an issue)
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### 📚 Description

Maybe fixes the errors reported at
#670 (comment).
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packages/storybook-addon/build.config.ts

@@ -35,6 +35,7 @@ export default defineBuildConfig({
     '#app/composables/state',
     '#app/entry',
     '#build/plugins',
+    '#build/css',
+    'virtual:nuxt-runtime-config',
   ],
-  failOnWarn: false,
 })