Open links in default browser

[cassidyjames]

I currently don't allow navigating away from the root domain, but it would be useful to allow it since the dashboard is just web-based, anyway. For example, on my Home Assistant dashboard I have a link out to the web version of my security camera interface because they offer more options there than through the API that Home Assistant can use (but I can't embed it in an iframe).

• Don't disallow navigating
• Throw a banner when not on the base domain
• Add a "back" or "close" button to return to the base domain

[cassidyjames]

Actually, it does currently allow navigating across sites, something on my dashboard was just broken. So I actually should do the opposite here, and open any external links externally instead of inside the app.