add no-JS progressive enhancement for all shop flows

Every key shop flow now works via plain HTML forms when JS is
unavailable. LiveView progressively enhances when JS connects.

- PDP: form wraps variant/qty/add-to-cart with action="/cart/add"
- Cart page: qty +/- and remove use form POST fallbacks
- Cart/search header icons are now links with phx-click enhancement
- Collection sort form has GET action + noscript submit button
- New /search page with form-based search for no-JS users
- CartController gains add/remove/update_item POST actions
- CartHook gains update_quantity_form and remove_item_form handlers
- Fix flaky analytics tests caused by event table pollution

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

test/berrypod_web/live/shop/cart_test.exs

@@ -68,41 +68,39 @@ defmodule BerrypodWeb.Shop.CartTest do
 
     test "incrementing quantity updates the display", %{
       conn: conn,
-      product: product,
       variant: variant
     } do
       {:ok, view, _html} = conn |> conn_with_cart(variant.id) |> live(~p"/cart")
 
       html =
         view
-        |> element("#main-content button[aria-label='Increase quantity of #{product.title}']")
-        |> render_click()
+        |> form("#main-content form[phx-submit='update_quantity_form']")
+        |> render_submit(%{"quantity" => "2"})
 
       assert html =~ "Quantity updated to 2"
     end
 
     test "decrementing to zero removes the item", %{
       conn: conn,
-      product: product,
       variant: variant
     } do
       {:ok, view, _html} = conn |> conn_with_cart(variant.id) |> live(~p"/cart")
 
       html =
         view
-        |> element("#main-content button[aria-label='Decrease quantity of #{product.title}']")
-        |> render_click()
+        |> form("#main-content form[phx-submit='update_quantity_form']")
+        |> render_submit(%{"quantity" => "0"})
 
       assert html =~ "Your basket is empty"
     end
 
-    test "remove button removes the item", %{conn: conn, product: product, variant: variant} do
+    test "remove button removes the item", %{conn: conn, variant: variant} do
       {:ok, view, _html} = conn |> conn_with_cart(variant.id) |> live(~p"/cart")
 
       html =
         view
-        |> element("#main-content button[aria-label='Remove #{product.title} from cart']")
-        |> render_click()
+        |> form("#main-content form[phx-submit='remove_item_form']")
+        |> render_submit()
 
       assert html =~ "Your basket is empty"
     end

test/berrypod_web/live/shop/product_show_test.exs

@@ -292,11 +292,11 @@ defmodule BerrypodWeb.Shop.ProductShowTest do
       view |> element("button[phx-click='increment_quantity']") |> render_click()
       view |> element("button[phx-click='increment_quantity']") |> render_click()
 
-      # Add to cart
+      # Add to cart via form submit
       html =
         view
-        |> element("button", "Add to basket")
-        |> render_click()
+        |> form("form[phx-submit='add_to_cart']")
+        |> render_submit()
 
       # Decrement should be disabled again (quantity reset to 1)
       assert html =~ ~s(phx-click="decrement_quantity")
@@ -310,8 +310,8 @@ defmodule BerrypodWeb.Shop.ProductShowTest do
 
       html =
         view
-        |> element("button", "Add to basket")
-        |> render_click()
+        |> form("form[phx-submit='add_to_cart']")
+        |> render_submit()
 
       assert html =~ "added to cart"
     end
@@ -321,8 +321,8 @@ defmodule BerrypodWeb.Shop.ProductShowTest do
 
       html =
         view
-        |> element("button", "Add to basket")
-        |> render_click()
+        |> form("form[phx-submit='add_to_cart']")
+        |> render_submit()
 
       assert html =~ "Mountain Sunrise Print"
     end

test/berrypod_web/live/shop/search_page_test.exs

@@ -0,0 +1,57 @@
+defmodule BerrypodWeb.Shop.SearchPageTest do
+  use BerrypodWeb.ConnCase, async: false
+
+  import Phoenix.LiveViewTest
+  import Berrypod.AccountsFixtures
+
+  alias Berrypod.ProductsFixtures
+
+  setup do
+    user_fixture()
+    {:ok, _} = Berrypod.Settings.set_site_live(true)
+    :ok
+  end
+
+  describe "GET /search" do
+    test "renders search page with empty query", %{conn: conn} do
+      {:ok, _view, html} = live(conn, ~p"/search")
+
+      assert html =~ "Search"
+      assert html =~ ~s(placeholder="Search products...")
+    end
+
+    test "renders search results for a matching query", %{conn: conn} do
+      product =
+        ProductsFixtures.complete_product_fixture(%{title: "Blue Mountain Print"})
+
+      Berrypod.Search.index_product(product)
+
+      {:ok, _view, html} = live(conn, ~p"/search?q=mountain")
+
+      assert html =~ "Blue Mountain Print"
+      assert html =~ "1 result"
+    end
+
+    test "renders no-results message for unmatched query", %{conn: conn} do
+      {:ok, _view, html} = live(conn, ~p"/search?q=nonexistent")
+
+      assert html =~ "No products found"
+    end
+
+    test "search form submits via LiveView and updates URL", %{conn: conn} do
+      product =
+        ProductsFixtures.complete_product_fixture(%{title: "Red Sunset Poster"})
+
+      Berrypod.Search.index_product(product)
+
+      {:ok, view, _html} = live(conn, ~p"/search")
+
+      html =
+        view
+        |> form(".search-page-form", %{"q" => "sunset"})
+        |> render_submit()
+
+      assert html =~ "Red Sunset Poster"
+    end
+  end
+end