Media item lifecycle improvements (#18)

* Added jobs for enqueuing/dequeuing media based on source's status

* adds lifecycle columns to source and media_item tables

priv/repo/migrations/20240210005919_add_lifecycle_columns_to_sources_and_media.exs

@@ -0,0 +1,14 @@
+defmodule Pinchflat.Repo.Migrations.AddLifecycleColumnsToSourcesAndMedia do
+  use Ecto.Migration
+
+  def change do
+    alter table(:media_items) do
+      add :media_downloaded_at, :utc_datetime
+      add :details_updated_at, :utc_datetime
+    end
+
+    alter table(:sources) do
+      add :last_indexed_at, :utc_datetime
+    end
+  end
+end