fix: normalize checkbox value and improve UI layout

- Normalize checkbox 'on' value to boolean true in settings
- Change Payment Data layout to flex-nowrap for horizontal display
- Replace membership fee type dropdown with display-only view
- Fix tests to use correct button selectors and switch to membership fees tab

lib/mv_web/live/member_live/show.ex

@@ -168,7 +168,7 @@ defmodule MvWeb.MemberLive.Show do
         <div class="max-w-xl">
           <.section_box title={gettext("Payment Data")}>
             <%= if @member.membership_fee_type do %>
-              <div class="flex gap-6 flex-wrap">
+              <div class="flex gap-6 flex-nowrap overflow-x-auto">
                 <.data_field
                   label={gettext("Type")}
                   value={@member.membership_fee_type.name}