Bring login and configuration pages in line with dashboard design

[beubax]

What happened?

The dashboard has a newer visual design, but other UI pages, especially login and configuration pages, still use older or inconsistent styling. This makes the product feel fragmented and less polished.

What did you expect?

Login and configuration pages should use the same design language as the dashboard, including layout, spacing, typography, color usage, buttons, forms, and empty/error/loading states.

Steps to reproduce

1. Open the dashboard UI.
2. Compare it with the login and configuration pages.
3. Note mismatches in layout, form styling, buttons, typography, spacing, and page structure.
4. Update those pages to follow the dashboard's design system and interaction patterns.