fix(membership-fees): show error for unparseable cycle date instead of crashing

Date.from_iso8601/1 returns {:error, reason}, so the with else clause matching a bare :error never fired and an invalid date raised a WithClauseError. Match the real date/calendar error reasons so the user sees the validation message.

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

@@ -1027,7 +1027,7 @@ defmodule MvWeb.MemberLive.Show.MembershipFeesComponent do
            |> assign(:create_cycle_error, format_error(error))}
       end
     else
-      :error ->
+      {:error, reason} when reason in [:invalid_format, :invalid_date, :incompatible_calendars] ->
         {:noreply,
          socket
          |> assign(:create_cycle_error, gettext("Invalid date format"))}