Adds indexes (#3035)

Going by common query patterns, these indexes seemed the most appropriate, at the time of this writing.

priv/repo/migrations/20240926095243_add_activity_log_index.exs

@@ -0,0 +1,8 @@
+defmodule Trento.Repo.Migrations.AddActivityLogIndex do
+  use Ecto.Migration
+
+  def change do
+    create index(:activity_logs, [:type])
+    create index(:activity_logs, [:actor])
+  end
+end