Add shield hostname rules migration (#3992)

priv/repo/migrations/20240407104659_shield_hostname_rules.exs

@@ -0,0 +1,17 @@
+defmodule Plausible.Repo.Migrations.ShieldHostnameRules do
+  use Ecto.Migration
+
+  def change do
+    create table(:shield_rules_hostname, primary_key: false) do
+      add(:id, :uuid, primary_key: true)
+      add :site_id, references(:sites, on_delete: :delete_all), null: false
+      add :hostname, :text, null: false
+      add :hostname_pattern, :text, null: false
+      add :action, :string, default: "allow", null: false
+      add :added_by, :string
+      timestamps()
+    end
+
+    create unique_index(:shield_rules_hostname, [:site_id, :hostname_pattern])
+  end
+end