Secure regenerate_cycles: require can?(:create, MembershipFeeCycle) in handler

- Handler returns flash error when non-admin triggers event (e.g. DevTools).
- Test: read_only cannot create MembershipFeeCycle so handler rejects.

lib/mv_web/live/member_live/show/membership_fees_component.ex

@@ -568,7 +568,10 @@ defmodule MvWeb.MemberLive.Show.MembershipFeesComponent do
   end
 
   def handle_event("regenerate_cycles", _params, socket) do
-    # Button is only shown when can_create_cycle (normal_user and admin). Cycle generation uses system actor.
+    # Server-side authorization: do not rely on UI hiding the button (e.g. read_only could trigger via DevTools).
+    actor = current_actor(socket)
+
+    if can?(actor, :create, MembershipFeeCycle) do
       socket = assign(socket, :regenerating, true)
       member = socket.assigns.member
 
@@ -608,6 +611,12 @@ defmodule MvWeb.MemberLive.Show.MembershipFeesComponent do
            |> assign(:regenerating, false)
            |> put_flash(:error, format_error(error))}
       end
+    else
+      {:noreply,
+       socket
+       |> assign(:regenerating, false)
+       |> put_flash(:error, format_error(%Ash.Error.Forbidden{}))}
+    end
   end
 
   def handle_event("edit_cycle_amount", %{"cycle_id" => cycle_id}, socket) do

test/mv_web/member_live/show_membership_fees_test.exs

@@ -320,6 +320,19 @@ defmodule MvWeb.MemberLive.ShowMembershipFeesTest do
     end
   end
 
+  describe "read_only cannot trigger regenerate_cycles (handler enforces can?)" do
+    @tag role: :read_only
+    test "read_only cannot create MembershipFeeCycle so regenerate_cycles handler would show flash error",
+         %{current_user: read_only_user} do
+      # The regenerate_cycles handler checks can?(actor, :create, MembershipFeeCycle) before
+      # calling the generator. If a read_only user triggered the event (e.g. via DevTools),
+      # the handler returns flash error and no new cycles are created.
+      # This test verifies the condition the handler uses.
+      refute MvWeb.Authorization.can?(read_only_user, :create, MembershipFeeCycle),
+             "read_only must not be allowed to create MembershipFeeCycle so handler rejects regenerate_cycles"
+    end
+  end
+
   describe "confirm_delete_all_cycles handler (policy enforced)" do
     @tag role: :admin
     test "admin can delete all cycles via UI and cycles are removed", %{conn: conn} do