fix: open guide in new tab

[condyl]

Closes #43

This pull request updates the NavbarComponent to support opening certain navigation links in a new browser tab.

Navigation link behavior improvements:

• Added a newTab property to the "Guide" navigation item, indicating it should open in a new tab.
• Updated the rendering logic in the mobile drawer to use an <a> tag with target="_blank" and rel="noopener noreferrer" for navigation items with newTab, falling back to <Link> for others.
• Applied the same conditional rendering logic to the desktop navigation bar, ensuring consistency across devices for links that should open in a new tab.