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/pages/editor.ex

@@ -32,6 +32,7 @@ defmodule BerrypodWeb.Admin.Pages.Editor do
      |> assign(:history, [])
      |> assign(:future, [])
      |> assign(:dirty, false)
+     |> assign(:save_status, :idle)
      |> assign(:show_picker, false)
      |> assign(:picker_filter, "")
      |> assign(:expanded, MapSet.new())
@@ -383,13 +384,18 @@ defmodule BerrypodWeb.Admin.Pages.Editor do
 
     case Pages.save_page(slug, %{title: page_data.title, blocks: blocks}) do
       {:ok, _page} ->
+        Process.send_after(self(), :clear_save_status, 3000)
+
         {:noreply,
          socket
          |> assign(:dirty, false)
-         |> put_flash(:info, "Page saved")}
+         |> assign(:save_status, :saved)}
 
       {:error, _changeset} ->
-        {:noreply, put_flash(socket, :error, "Failed to save page")}
+        {:noreply,
+         socket
+         |> assign(:save_status, :error)
+         |> put_flash(:error, "Failed to save page")}
     end
   end
 
@@ -515,6 +521,13 @@ defmodule BerrypodWeb.Admin.Pages.Editor do
     end
   end
 
+  # ── Handle info ──────────────────────────────────────────────────
+
+  @impl true
+  def handle_info(:clear_save_status, socket) do
+    {:noreply, assign(socket, :save_status, :idle)}
+  end
+
   # ── Render ───────────────────────────────────────────────────────
 
   @impl true
@@ -586,6 +599,7 @@ defmodule BerrypodWeb.Admin.Pages.Editor do
           >
             Save
           </button>
+          <.inline_feedback status={@save_status} />
         </:actions>
       </.header>