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/settings.ex

@@ -16,6 +16,8 @@ defmodule BerrypodWeb.Admin.Settings do
      |> assign(:site_live, Settings.site_live?())
      |> assign(:cart_recovery_enabled, Settings.abandoned_cart_recovery_enabled?())
      |> assign(:from_address, Settings.get_setting("email_from_address") || user.email)
+     |> assign(:from_address_status, :idle)
+     |> assign(:signing_secret_status, :idle)
      |> assign_stripe_state()
      |> assign_products_state()
      |> assign_account_state(user)}
@@ -116,11 +118,12 @@ defmodule BerrypodWeb.Admin.Settings do
 
     if address != "" do
       Settings.put_setting("email_from_address", address)
+      Process.send_after(self(), :clear_from_address_status, 3000)
 
       {:noreply,
        socket
        |> assign(:from_address, address)
-       |> put_flash(:info, "From address saved")}
+       |> assign(:from_address_status, :saved)}
     else
       {:noreply, put_flash(socket, :error, "From address can't be blank")}
     end
@@ -181,11 +184,12 @@ defmodule BerrypodWeb.Admin.Settings do
       {:noreply, put_flash(socket, :error, "Please enter a signing secret")}
     else
       StripeSetup.save_signing_secret(secret)
+      Process.send_after(self(), :clear_signing_secret_status, 3000)
 
       socket =
         socket
         |> assign_stripe_state()
-        |> put_flash(:info, "Webhook signing secret saved")
+        |> assign(:signing_secret_status, :saved)
 
       {:noreply, socket}
     end
@@ -289,6 +293,17 @@ defmodule BerrypodWeb.Admin.Settings do
     end
   end
 
+  # -- Clear status messages --
+
+  @impl true
+  def handle_info(:clear_from_address_status, socket) do
+    {:noreply, assign(socket, :from_address_status, :idle)}
+  end
+
+  def handle_info(:clear_signing_secret_status, socket) do
+    {:noreply, assign(socket, :signing_secret_status, :idle)}
+  end
+
   # -- Render --
 
   @impl true
@@ -364,6 +379,7 @@ defmodule BerrypodWeb.Admin.Settings do
             stripe_has_signing_secret={@stripe_has_signing_secret}
             secret_form={@secret_form}
             advanced_open={@stripe_advanced_open}
+            signing_secret_status={@signing_secret_status}
           />
         <% end %>
       </section>
@@ -448,6 +464,7 @@ defmodule BerrypodWeb.Admin.Settings do
               placeholder="noreply@yourshop.com"
             />
             <.button phx-disable-with="Saving...">Save</.button>
+            <.inline_feedback status={@from_address_status} />
           </form>
         </div>
       </section>
@@ -704,6 +721,7 @@ defmodule BerrypodWeb.Admin.Settings do
           />
           <div class="admin-form-actions-sm">
             <.button phx-disable-with="Saving...">Save signing secret</.button>
+            <.inline_feedback status={@signing_secret_status} />
           </div>
         </.form>
       <% else %>
@@ -733,6 +751,7 @@ defmodule BerrypodWeb.Admin.Settings do
                 />
                 <div class="admin-form-actions-sm">
                   <.button phx-disable-with="Saving...">Save signing secret</.button>
+                  <.inline_feedback status={@signing_secret_status} />
                 </div>
               </.form>
             </div>