feat: more stuff around persistence of data

lib/bds/settings/setting.ex

@@ -0,0 +1,19 @@
+defmodule BDS.Settings.Setting do
+  @moduledoc false
+
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  @primary_key {:key, :string, autogenerate: false}
+
+  schema "settings" do
+    field :value, :string
+    field :updated_at, :integer
+  end
+
+  def changeset(setting, attrs) do
+    setting
+    |> cast(attrs, [:key, :value, :updated_at], empty_values: [nil])
+    |> validate_required([:key, :value, :updated_at])
+  end
+end