Update migrations

priv/repo/migrations/20250615131856_create_activities.exs

@@ -0,0 +1,18 @@
+defmodule Nulla.Repo.Migrations.CreateActivities do
+  use Ecto.Migration
+
+  def change do
+    create table(:activities, primary_key: false) do
+      add :id, :bigint, primary_key: true
+      add :type, :string, null: false
+      add :actor, :string, null: false
+      add :object, :map, null: false
+      add :to, {:array, :string}, default: []
+
+      timestamps()
+    end
+
+    create index(:activities, [:actor])
+    create index(:activities, [:type])
+  end
+end