Simple admin dashboard for A/I.

Contains links to useful internal systems and account management tools.

The HTTP server serves static files but also proxies requests to some backends we're interested in (prometheus, alertmanager). This is necessary because we can't do client-side requests to these other services on other domains due to browser's CORS policies: in practice, CORS prevents the single-sign on request flow (through the sso-server and back) to work because redirects are forbidden by CORS.