feat: new configuration system (and schema) (#2819)

Procfile.dev

@@ -1,3 +1,3 @@
-web: bundle exec puma -C config/puma.rb
+web: unset PORT; bundle exec puma -C config/puma.rb
 worker: bundle exec ruby script/worker.rb
-smtp: bundle exec ruby script/smtp_server.rb
+smtp: unset PORT; bundle exec ruby script/smtp_server.rb