refactor: update migration for UUIDv7 and explicit FK constraint

- Add on_delete: :restrict to users.role_id foreign key
- Update roles.id to use uuid_generate_v7() default
- Regenerate resource snapshots

priv/repo/migrations/20260106165250_update_role_to_uuidv7.exs

@@ -0,0 +1,21 @@
+defmodule Mv.Repo.Migrations.UpdateRoleToUuidv7 do
+  @moduledoc """
+  Updates resources based on their most recent snapshots.
+
+  This file was autogenerated with `mix ash_postgres.generate_migrations`
+  """
+
+  use Ecto.Migration
+
+  def up do
+    alter table(:roles) do
+      modify :id, :uuid, default: fragment("uuid_generate_v7()")
+    end
+  end
+
+  def down do
+    alter table(:roles) do
+      modify :id, :uuid, default: fragment("gen_random_uuid()")
+    end
+  end
+end