feat: new background work process

This removes all previous dependencies on RabbitMQ and the need to run separate cron and requeueing processes.

app/models/scheduled_task.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: scheduled_tasks
+#
+#  id             :bigint           not null, primary key
+#  name           :string(255)
+#  next_run_after :datetime
+#
+# Indexes
+#
+#  index_scheduled_tasks_on_name  (name) UNIQUE
+#
+class ScheduledTask < ApplicationRecord
+end