feat: add health server and prometheus metrics to worker

script/smtp_server.rb

@@ -4,4 +4,6 @@ $stdout.sync = true
 $stderr.sync = true
 
 require_relative "../config/environment"
+
+HealthServer.start(name: "smtp-server", default_port: 9091)
 SMTPServer::Server.new(debug: true).run

script/worker.rb

@@ -5,4 +5,6 @@ $stdout.sync = true
 $stderr.sync = true
 
 require_relative "../config/environment"
+
+HealthServer.start(name: "worker", default_port: 9090)
 Worker::Process.new.run