Switch from custom / simple-http-server web serving to Caddy

[shah]

Instead of having multiple services for sandbox (Deno) vs. dev (simple-http-server) vs. production (Traefik) we should moved to a unified Caddy-based strategy:

• Switch from Deno pubctl.ts experimental / sandbox model to deno_fcgi via Caddy with spawn-fcgi/FCGI::Spawn for serving hot-reloadable / watchable builds
• Switch from simple-http-server to Caddy (see config hints for configuring spawn-fcgi).
  • Add a caddy parameter to pubctl.ts (similar to serve) that would generate a Caddyfile for execution after all other resources were created. This way no separate execution script is required.
• Consider using Caddy in production with oAuth support instead of Traefik with oauth_proxy
• Consider using Pglet approach to "micro apps" by integrating a single service point and then, similar to CGI or FastCGI, allowing applets to be created

In case we need native websockets:

• Check out websocketd