feat: make login button show only on dekstop (#6213)

## Summary

Make login and current user button visible on desktop only. 

## Screenshots (if applicable)

<img width="519" height="162" alt="image"
src="https://github.com/user-attachments/assets/80d86145-2bb9-4396-a02d-dc577192cb17"
/>
<img width="482" height="130" alt="image"
src="https://github.com/user-attachments/assets/cd843611-ce23-4cd4-a864-78cac1c7101f"
/>

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6213-feat-make-login-button-show-only-on-dekstop-2956d73d365081eb93f1d5da92dc38ee)
by [Unito](https://www.unito.io)

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Co-authored-by: github-actions <[email protected]>

Author: simula-r