Install Oban with dedicated repo

priv/background_repo/migrations/20250413170433_create_jobs_table.exs

@@ -0,0 +1,13 @@
+defmodule MusicLibrary.BackgroundRepo.Migrations.CreateJobsTable do
+  use Ecto.Migration
+
+  def up do
+    Oban.Migration.up(version: 12)
+  end
+
+  # We specify `version: 1` in `down`, ensuring that we'll roll all the way back down if
+  # necessary, regardless of which version we've migrated `up` to.
+  def down do
+    Oban.Migration.down(version: 1)
+  end
+end