fix PDP quantity selector and trust badge consistency

Wire up +/− buttons with phx-click events and handle_event handlers,
clamp to 1–99, reset to 1 after add-to-cart. Trust badges now use a
single hero-check-circle icon and sentence case text.

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

test/simpleshop_theme_web/live/shop_live/product_show_test.exs

@@ -104,6 +104,67 @@ defmodule SimpleshopThemeWeb.ShopLive.ProductShowTest do
     end
   end
 
+  describe "Quantity selector" do
+    test "renders quantity selector with initial value of 1", %{conn: conn} do
+      {:ok, view, _html} = live(conn, ~p"/products/1")
+
+      assert has_element?(view, "button[phx-click='decrement_quantity']")
+      assert has_element?(view, "button[phx-click='increment_quantity']")
+    end
+
+    test "decrement button is disabled at quantity 1", %{conn: conn} do
+      {:ok, view, _html} = live(conn, ~p"/products/1")
+
+      assert has_element?(view, "button[phx-click='decrement_quantity'][disabled]")
+    end
+
+    test "increment increases quantity", %{conn: conn} do
+      {:ok, view, _html} = live(conn, ~p"/products/1")
+
+      html =
+        view
+        |> element("button[phx-click='increment_quantity']")
+        |> render_click()
+
+      # Quantity should now be 2, decrement no longer disabled
+      refute html =~ ~s(phx-click="decrement_quantity" disabled)
+    end
+
+    test "decrement decreases quantity", %{conn: conn} do
+      {:ok, view, _html} = live(conn, ~p"/products/1")
+
+      # Increment twice to get to 3
+      view |> element("button[phx-click='increment_quantity']") |> render_click()
+      view |> element("button[phx-click='increment_quantity']") |> render_click()
+
+      html =
+        view
+        |> element("button[phx-click='decrement_quantity']")
+        |> render_click()
+
+      # Should be back to 2 — decrement still enabled
+      refute html =~ ~s(phx-click="decrement_quantity" disabled)
+    end
+
+    test "quantity resets to 1 after adding to cart", %{conn: conn} do
+      {:ok, view, _html} = live(conn, ~p"/products/1")
+
+      # Increment to 3
+      view |> element("button[phx-click='increment_quantity']") |> render_click()
+      view |> element("button[phx-click='increment_quantity']") |> render_click()
+
+      # Add to cart
+      html =
+        view
+        |> element("button", "Add to basket")
+        |> render_click()
+
+      # Decrement should be disabled again (quantity reset to 1)
+      assert html =~ ~s(phx-click="decrement_quantity")
+      assert html =~ "disabled"
+    end
+  end
+
   describe "Add to cart" do
     test "add to cart opens the cart drawer", %{conn: conn} do
       {:ok, view, _html} = live(conn, ~p"/products/1")