fix(OnyxNavBar): support SSR

[larsrickert]

Relates to #1073

Fix error when using the nav bar with Nuxt / server side rendering

Checklist

• [x] The added / edited code has been documented with JSDoc
• [x] A changeset is added with npx changeset add if your changes should be released as npm package (because they affect the library usage)

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: da8512bcddd9fe77530992af9b6a17c1dd4a6f4a

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 7 packages

| Name | Type | | ------------------------- | ----- | | sit-onyx | Patch | | alpha-test-app | Patch | | playground | Patch | | @sit-onyx/chartjs-plugin | Patch | | @sit-onyx/nuxt | Patch | | @sit-onyx/storybook-utils | Patch | | @sit-onyx/vitepress-theme | Patch |

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