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/membership_fee_settings_live.ex

@@ -30,11 +30,39 @@ defmodule MvWeb.MembershipFeeSettingsLive do
 
   @impl true
   def handle_event("validate", %{"settings" => params}, socket) do
-    {:noreply, assign(socket, form: AshPhoenix.Form.validate(socket.assigns.form, params))}
+    # Normalize checkbox value: "on" -> true, missing -> false
+    normalized_params =
+      if Map.has_key?(params, "include_joining_cycle") do
+        params
+        |> Map.update("include_joining_cycle", false, fn
+          "on" -> true
+          "true" -> true
+          true -> true
+          _ -> false
+        end)
+      else
+        Map.put(params, "include_joining_cycle", false)
+      end
+
+    {:noreply, assign(socket, form: AshPhoenix.Form.validate(socket.assigns.form, normalized_params))}
   end
 
   def handle_event("save", %{"settings" => params}, socket) do
-    case AshPhoenix.Form.submit(socket.assigns.form, params: params) do
+    # Normalize checkbox value: "on" -> true, missing -> false
+    normalized_params =
+      if Map.has_key?(params, "include_joining_cycle") do
+        params
+        |> Map.update("include_joining_cycle", false, fn
+          "on" -> true
+          "true" -> true
+          true -> true
+          _ -> false
+        end)
+      else
+        Map.put(params, "include_joining_cycle", false)
+      end
+
+    case AshPhoenix.Form.submit(socket.assigns.form, params: normalized_params) do
       {:ok, updated_settings} ->
         {:noreply,
          socket