test(membership-fees): share create_fee_type and create_cycle fixtures

Replace the create_fee_type/create_cycle helpers duplicated across 18/8
membership-fee test files with a single shared definition in Mv.Fixtures,
reconciling the divergent local signatures (including the reversed
argument order) into one superset so behavior is unchanged.

test/mv/membership_fees/cycle_generator_test.exs

@@ -4,9 +4,10 @@ defmodule Mv.MembershipFees.CycleGeneratorTest do
   """
   use Mv.DataCase, async: false
 
+  import Mv.Fixtures, only: [create_fee_type: 2]
+
   alias Mv.MembershipFees.CycleGenerator
   alias Mv.MembershipFees.MembershipFeeCycle
-  alias Mv.MembershipFees.MembershipFeeType
 
   require Ash.Query
 
@@ -15,21 +16,6 @@ defmodule Mv.MembershipFees.CycleGeneratorTest do
     %{actor: system_actor}
   end
 
-  # Helper to create a membership fee type
-  defp create_fee_type(attrs, actor) do
-    default_attrs = %{
-      name: "Test Fee Type #{System.unique_integer([:positive])}",
-      amount: Decimal.new("50.00"),
-      interval: :yearly
-    }
-
-    attrs = Map.merge(default_attrs, attrs)
-
-    MembershipFeeType
-    |> Ash.Changeset.for_create(:create, attrs)
-    |> Ash.create!(actor: actor)
-  end
-
   # Helper to create a member without triggering cycle generation
   defp create_member_without_cycles(attrs, actor) do
     default_attrs = %{