migrate admin forms to inline feedback

Replace put_flash calls with inline feedback for form saves:
- Email settings: "Now send a test email" after saving
- Settings: from address and signing secret saves
- Page editor: save button shows "Saved" checkmark

Inline feedback appears next to save buttons and auto-clears after
3 seconds. Banners (put_flash) remain for page-level outcomes like
deletions, state changes, and async operations.

Task 3 of notification overhaul. Theme editor skipped as it auto-saves.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/berrypod_web/live/admin/email_settings.ex

@@ -37,6 +37,7 @@ defmodule BerrypodWeb.Admin.EmailSettings do
      |> assign(:test_retryable, false)
      |> assign(:from_checklist, false)
      |> assign(:field_errors, flash_errors)
+     |> assign(:save_status, :idle)
      |> assign(:form, to_form(%{}, as: :email))}
   end
 
@@ -93,6 +94,8 @@ defmodule BerrypodWeb.Admin.EmailSettings do
              socket.assigns.current_scope.user.email
            ) do
         {:ok, _adapter_info} ->
+          Process.send_after(self(), :clear_save_status, 3000)
+
           {:noreply,
            socket
            |> assign(:adapter_key, adapter_key)
@@ -102,7 +105,7 @@ defmodule BerrypodWeb.Admin.EmailSettings do
            |> assign(:field_errors, %{})
            |> assign(:test_result, nil)
            |> assign(:test_error, nil)
-           |> put_flash(:info, "Settings saved — send a test email to check it works")}
+           |> assign(:save_status, :saved)}
 
         {:error, field_errors} when is_map(field_errors) ->
           {:noreply, assign(socket, :field_errors, field_errors)}
@@ -142,6 +145,10 @@ defmodule BerrypodWeb.Admin.EmailSettings do
   # Swoosh test adapter sends {:email, ...} messages — ignore them
   def handle_info({:email, _}, socket), do: {:noreply, socket}
 
+  def handle_info(:clear_save_status, socket) do
+    {:noreply, assign(socket, :save_status, :idle)}
+  end
+
   @impl true
   def render(assigns) do
     ~H"""
@@ -235,6 +242,7 @@ defmodule BerrypodWeb.Admin.EmailSettings do
             values={@all_values[adapter.key] || %{}}
             field_errors={if(@adapter_key == adapter.key, do: @field_errors, else: %{})}
             env_locked={@env_locked}
+            save_status={if(@adapter_key == adapter.key, do: @save_status, else: :idle)}
           />
         </.form>
       </section>
@@ -336,6 +344,7 @@ defmodule BerrypodWeb.Admin.EmailSettings do
   attr :values, :map, required: true
   attr :field_errors, :map, required: true
   attr :env_locked, :boolean, required: true
+  attr :save_status, :atom, default: :idle
 
   defp adapter_config(assigns) do
     ~H"""
@@ -377,6 +386,7 @@ defmodule BerrypodWeb.Admin.EmailSettings do
             <.button phx-disable-with="Saving...">
               Save settings
             </.button>
+            <.inline_feedback status={@save_status} message="Now send a test email" />
           </div>
         <% end %>
       </div>