Environment URLs checks

A failed connection to your app used to just fail. Now Thunders tells you why.

• DNS doesn't resolve: Thunders says so, and suggests a fix if the hostname looks like a typo.
• A TLS problem: see the exact certificate issue, with an optional setting to ignore HTTPS certificate errors for testing.
• A timeout or refused connection: get pointed at a likely firewall issue, with our egress IPs ready to copy into your allowlist.
• An HTTP error from your app itself: a 401 points you at your credentials, a 5xx suggests checking the app is actually up.
• A captcha blocking the login step: a guided card walks you through adding a bypass flag to your app, and turning it on.

Instead of a generic failure, you get pointed at the actual problem, and usually a way to fix it on the spot.

#Sprint31