Fix SigningKey db schema

priv/repo/migrations/20250112000000_signing_key_nullability.exs

@@ -0,0 +1,24 @@
+defmodule Pleroma.Repo.Migrations.SigningKeyNullability do
+  use Ecto.Migration
+
+  import Ecto.Query
+
+  def up() do
+    # Delete existing NULL entries; they are useless
+    Pleroma.User.SigningKey
+    |> where([s], is_nil(s.user_id) or is_nil(s.public_key))
+    |> Pleroma.Repo.delete_all()
+
+    alter table(:signing_keys) do
+      modify :user_id, :uuid, null: false
+      modify :public_key, :text, null: false
+    end
+  end
+
+  def down() do
+    alter table(:signing_keys) do
+      modify :user_id, :uuid, null: true
+      modify :public_key, :text, null: true
+    end
+  end
+end