Our health check endpoint (https://dev.coder.com/api/v2/debug/health) returns a pass bool, which is calculated based on whether any of the DERP regions return an error. I'm proposing we:

• Change pass to also calculated based on whether the access URL is reachable, WebSockets work, and any other top-level checks (healthcheck endpoint: minor improvements to pass + show failure reason #7745)
• Add a top-level fail_reason (naming TBD) so that the user (or client-side frontend) does not have to grep through errors to determine why the health check failed.