Add models and migrations

priv/repo/migrations/20250604083506_create_notes.exs

@@ -0,0 +1,18 @@
+defmodule Nulla.Repo.Migrations.CreateNotes do
+  use Ecto.Migration
+
+  def change do
+    create table(:notes) do
+      add :content, :string
+      add :visibility, :string, default: "public"
+      add :sensitive, :boolean, default: false
+      add :language, :string
+      add :in_reply_to, :string
+      add :user_id, references(:users, on_delete: :delete_all)
+
+      timestamps(type: :utc_datetime)
+    end
+
+    create index(:notes, [:user_id])
+  end
+end