use citext for key column

Author: zcesur

priv/repo/migrations/20250903171044_make_settings_key_citext.exs

@@ -0,0 +1,9 @@
+defmodule Algora.Repo.Migrations.MakeSettingsKeyCitext do
+  use Ecto.Migration
+
+  def change do
+    alter table(:settings) do
+      modify :key, :citext
+    end
+  end
+end