add no-JS fallback for provider forms

Progressive enhancement: provider form now works without JavaScript.
Forms POST to ProvidersController (create/update), which handles
validation and redirects with flash messages.

With JS: LiveView phx-submit handles save, navigates with flash.
Without JS: Form POSTs to controller, redirects with flash.

Completes Task 3 of notification overhaul (admin forms migration).

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

PROGRESS.md

@@ -29,7 +29,7 @@ Tier 1 MVP complete. Tier 2 production readiness complete (except Litestream and
 - Fully Tailwind-free CSS (12 KB gzipped shop+theme, 95 KB gzipped admin total)
 - CI pipeline (compile warnings, format, credo, dialyzer, tests)
 - Deployed on Fly.io with observability (LiveDashboard, ErrorTracker, structured logging)
-- 1716+ tests passing, 99-100 PageSpeed mobile
+- 1759+ tests passing, 99-100 PageSpeed mobile
 
 ## Next up
 
@@ -75,7 +75,7 @@ Replace floating toast/flash messages with inline feedback and persistent top ba
 |---|------|-----|--------|
 | 1 | Build inline feedback component | 1.5h | done |
 | 2 | Build persistent top banner component (replaces flash) | 1.5h | done |
-| 3 | Migrate admin forms to inline feedback (theme, pages, settings, email, providers) | 3h | in progress |
+| 3 | Migrate admin forms to inline feedback (theme, pages, settings, email, providers) | 3h | done |
 | 4 | Migrate remaining admin pages (media, products, activity, newsletter, redirects, nav) | 2h | planned |
 | 5 | Migrate shop pages (cart, contact, checkout, auth) | 2h | planned |
 | 6 | Migrate setup wizard notifications | 1h | planned |

lib/berrypod_web/controllers/providers_controller.ex

@@ -0,0 +1,54 @@
+defmodule BerrypodWeb.ProvidersController do
+  @moduledoc """
+  No-JS fallback for provider connection forms.
+
+  With JS enabled, the LiveView handles everything. Without JS,
+  the form POSTs here and we redirect back to the settings page.
+  """
+  use BerrypodWeb, :controller
+
+  alias Berrypod.{KeyValidation, Products}
+  alias Berrypod.Providers.Provider
+
+  def create(conn, %{"provider_connection" => params}) do
+    api_key = params["api_key"]
+    provider_type = params["provider_type"]
+    provider = Provider.get(provider_type)
+
+    case KeyValidation.validate_provider_key(api_key, provider_type) do
+      {:error, message} ->
+        conn
+        |> put_flash(:error, message)
+        |> redirect(to: ~p"/admin/providers/new?type=#{provider_type}")
+
+      {:ok, api_key} ->
+        case Products.connect_provider(api_key, provider_type) do
+          {:ok, _connection} ->
+            conn
+            |> put_flash(:info, "Connected to #{provider.name}!")
+            |> redirect(to: ~p"/admin/settings")
+
+          {:error, _reason} ->
+            conn
+            |> put_flash(:error, "Could not connect. Check your API key and try again")
+            |> redirect(to: ~p"/admin/providers/new?type=#{provider_type}")
+        end
+    end
+  end
+
+  def update(conn, %{"id" => id, "provider_connection" => params}) do
+    connection = Products.get_provider_connection!(id)
+
+    case Products.update_provider_connection(connection, params) do
+      {:ok, _connection} ->
+        conn
+        |> put_flash(:info, "Settings saved")
+        |> redirect(to: ~p"/admin/settings")
+
+      {:error, _changeset} ->
+        conn
+        |> put_flash(:error, "Could not save settings")
+        |> redirect(to: ~p"/admin/providers/#{id}/edit")
+    end
+  end
+end

lib/berrypod_web/live/admin/providers/form.html.heex

@@ -27,7 +27,18 @@
     </div>
   <% end %>
 
-  <.form for={@form} id="provider-form" phx-change="validate" phx-submit="save">
+  <.form
+    for={@form}
+    id="provider-form"
+    action={
+      if @live_action == :new,
+        do: ~p"/admin/providers",
+        else: ~p"/admin/providers/#{@connection.id}"
+    }
+    method="post"
+    phx-change="validate"
+    phx-submit="save"
+  >
     <input type="hidden" name="provider_connection[provider_type]" value={@provider_type} />
 
     <.input

lib/berrypod_web/router.ex

@@ -144,6 +144,8 @@ defmodule BerrypodWeb.Router do
     post "/settings/from-address", SettingsController, :update_from_address
     post "/settings/stripe/signing-secret", SettingsController, :update_signing_secret
     post "/navigation", NavigationController, :save
+    post "/providers", ProvidersController, :create
+    post "/providers/:id", ProvidersController, :update
 
     live_session :admin,
       layout: {BerrypodWeb.Layouts, :admin},