feat: add Printify order submission and fulfilment tracking

Submit paid orders to Printify via provider API with idempotent
guards, Stripe address mapping, and error handling. Track fulfilment
status through submitted → processing → shipped → delivered via
webhook-driven updates (primary) and Oban Cron polling fallback.

- 9 fulfilment fields on orders (status, provider IDs, tracking, timestamps)
- OrderSubmissionWorker with retry logic, auto-enqueued after Stripe payment
- FulfilmentStatusWorker polls every 30 mins for missed webhook events
- Printify order webhook handlers (sent-to-production, shipment, delivered)
- Admin UI: fulfilment column in table, fulfilment card with tracking info,
  submit/retry and refresh buttons on order detail
- Mox provider mocking for test isolation (Provider.for_type configurable)
- 33 new tests (555 total), verified against real Printify API

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

test/support/fixtures/orders_fixtures.ex

@@ -5,12 +5,14 @@ defmodule SimpleshopTheme.OrdersFixtures do
 
   alias SimpleshopTheme.Orders
 
+  import SimpleshopTheme.ProductsFixtures
+
   def order_fixture(attrs \\ %{}) do
     attrs = Enum.into(attrs, %{})
 
     items = [
       %{
-        variant_id: "var_#{System.unique_integer([:positive])}",
+        variant_id: Map.get(attrs, :variant_id, "var_#{System.unique_integer([:positive])}"),
         name: Map.get(attrs, :product_name, "Test product"),
         variant: Map.get(attrs, :variant_title, "Red / Large"),
         price: Map.get(attrs, :unit_price, 1999),
@@ -26,6 +28,17 @@ defmodule SimpleshopTheme.OrdersFixtures do
 
     {:ok, order} = Orders.create_order(order_attrs)
 
+    # Apply shipping address if provided
+    order =
+      case attrs[:shipping_address] do
+        nil ->
+          order
+
+        addr ->
+          {:ok, order} = Orders.update_order(order, %{shipping_address: addr})
+          order
+      end
+
     case attrs[:payment_status] do
       "paid" ->
         {:ok, order} = Orders.mark_paid(order, "pi_test_#{System.unique_integer([:positive])}")
@@ -39,4 +52,59 @@ defmodule SimpleshopTheme.OrdersFixtures do
         order
     end
   end
+
+  @doc """
+  Creates a paid order with real product variants in the DB,
+  so enrich_items/1 can look up provider IDs. Also sets a shipping
+  address matching Stripe's format.
+
+  Returns `{order, variant, product, conn}`.
+  """
+  def paid_order_with_products_fixture(attrs \\ %{}) do
+    attrs = Enum.into(attrs, %{})
+    conn = provider_connection_fixture(%{provider_type: "printify"})
+    product = product_fixture(%{provider_connection: conn})
+    variant = product_variant_fixture(%{product: product})
+
+    shipping =
+      Map.get(attrs, :shipping_address, %{
+        "name" => "Jane Doe",
+        "line1" => "42 Test Street",
+        "line2" => nil,
+        "city" => "London",
+        "postal_code" => "SW1A 1AA",
+        "state" => nil,
+        "country" => "GB"
+      })
+
+    order =
+      order_fixture(%{
+        variant_id: variant.id,
+        payment_status: "paid",
+        shipping_address: shipping,
+        customer_email: Map.get(attrs, :customer_email, "buyer@example.com")
+      })
+
+    {order, variant, product, conn}
+  end
+
+  @doc """
+  Creates a submitted order (has provider_order_id set).
+  Returns `{order, variant, product, conn}`.
+  """
+  def submitted_order_fixture(attrs \\ %{}) do
+    {order, variant, product, conn} = paid_order_with_products_fixture(attrs)
+
+    attrs = Enum.into(attrs, %{})
+
+    {:ok, order} =
+      Orders.update_fulfilment(order, %{
+        fulfilment_status: "submitted",
+        provider_order_id:
+          Map.get(attrs, :provider_order_id, "printify_#{System.unique_integer([:positive])}"),
+        submitted_at: DateTime.utc_now() |> DateTime.truncate(:second)
+      })
+
+    {order, variant, product, conn}
+  end
 end