add CI pipeline with credo and dialyzer

mix ci alias: compile --warning-as-errors, format --check-formatted,
credo, dialyzer, test. Credo configured with sensible defaults.
Dialyzer ignore file for false positives (Stripe types, Mix tasks,
ExUnit internals). Credo fixes: map_join, filter consolidation,
nesting extraction, cond→if simplification.

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

lib/simpleshop_theme/clients/printify.ex

@@ -89,7 +89,7 @@ defmodule SimpleshopTheme.Clients.Printify do
   """
   def get_shop_id do
     case get_shops() do
-      {:ok, shops} when is_list(shops) and length(shops) > 0 ->
+      {:ok, shops} when is_list(shops) and shops != [] ->
         {:ok, hd(shops)["id"]}
 
       {:ok, []} ->

lib/simpleshop_theme/mockups/generator.ex

@@ -214,7 +214,7 @@ defmodule SimpleshopTheme.Mockups.Generator do
   """
   def find_print_provider(blueprint_id) do
     case Client.get_print_providers(blueprint_id) do
-      {:ok, providers} when is_list(providers) and length(providers) > 0 ->
+      {:ok, providers} when is_list(providers) and providers != [] ->
         # Just pick the first provider for simplicity
         {:ok, hd(providers)}
 

lib/simpleshop_theme/orders/fulfilment_status_worker.ex

@@ -23,24 +23,27 @@ defmodule SimpleshopTheme.Orders.FulfilmentStatusWorker do
       Logger.info("Polling fulfilment status for #{length(orders)} order(s)")
 
       Enum.each(orders, fn order ->
-        case Orders.refresh_fulfilment_status(order) do
-          {:ok, updated} ->
-            if updated.fulfilment_status != order.fulfilment_status do
-              Logger.info(
-                "Order #{order.order_number} status: #{order.fulfilment_status} → #{updated.fulfilment_status}"
-              )
-            end
-
-          {:error, reason} ->
-            Logger.warning(
-              "Failed to refresh status for order #{order.order_number}: #{inspect(reason)}"
-            )
-        end
-
+        refresh_order(order)
         Process.sleep(200)
       end)
 
       :ok
     end
   end
+
+  defp refresh_order(order) do
+    case Orders.refresh_fulfilment_status(order) do
+      {:ok, updated} ->
+        if updated.fulfilment_status != order.fulfilment_status do
+          Logger.info(
+            "Order #{order.order_number} status: #{order.fulfilment_status} → #{updated.fulfilment_status}"
+          )
+        end
+
+      {:error, reason} ->
+        Logger.warning(
+          "Failed to refresh status for order #{order.order_number}: #{inspect(reason)}"
+        )
+    end
+  end
 end

lib/simpleshop_theme/providers/printify.ex

@@ -146,21 +146,22 @@ defmodule SimpleshopTheme.Providers.Printify do
       true ->
         with api_key when is_binary(api_key) <- ProviderConnection.get_api_key(conn),
              :ok <- set_api_key(api_key) do
-          results =
-            Enum.map(@webhook_events, fn event ->
-              case Client.create_webhook(shop_id, webhook_url, event, secret) do
-                {:ok, response} -> {:ok, event, response}
-                {:error, reason} -> {:error, event, reason}
-              end
-            end)
-
-          {:ok, results}
+          {:ok, create_all_webhooks(shop_id, webhook_url, secret)}
         else
           nil -> {:error, :no_api_key}
         end
     end
   end
 
+  defp create_all_webhooks(shop_id, webhook_url, secret) do
+    Enum.map(@webhook_events, fn event ->
+      case Client.create_webhook(shop_id, webhook_url, event, secret) do
+        {:ok, response} -> {:ok, event, response}
+        {:error, reason} -> {:error, event, reason}
+      end
+    end)
+  end
+
   @doc """
   Lists registered webhooks for the shop.
   """

lib/simpleshop_theme/theme/fonts.ex

@@ -128,9 +128,7 @@ defmodule SimpleshopTheme.Theme.Fonts do
         [heading_key, body_key]
       end
 
-    font_keys
-    |> Enum.map(&generate_font_face_for_font(&1, path_resolver))
-    |> Enum.join("\n")
+    Enum.map_join(font_keys, "\n", &generate_font_face_for_font(&1, path_resolver))
   end
 
   @doc """
@@ -143,8 +141,7 @@ defmodule SimpleshopTheme.Theme.Fonts do
   def generate_all_font_faces(path_resolver \\ &default_path_resolver/1) do
     @fonts
     |> Map.keys()
-    |> Enum.map(&generate_font_face_for_font(&1, path_resolver))
-    |> Enum.join("\n")
+    |> Enum.map_join("\n", &generate_font_face_for_font(&1, path_resolver))
   end
 
   @doc """
@@ -213,8 +210,7 @@ defmodule SimpleshopTheme.Theme.Fonts do
   defp generate_font_face_for_font(key, path_resolver) do
     case get_font(key) do
       %{family: family, file_prefix: prefix, weights: weights} ->
-        weights
-        |> Enum.map(fn weight ->
+        Enum.map_join(weights, "", fn weight ->
           weight_suffix = if weight == 400, do: "regular", else: to_string(weight)
           font_path = path_resolver.("/fonts/#{prefix}-#{weight_suffix}.woff2")
 
@@ -228,7 +224,6 @@ defmodule SimpleshopTheme.Theme.Fonts do
           }
           """
         end)
-        |> Enum.join("")
 
       nil ->
         ""

lib/simpleshop_theme/theme/preview_data.ex

@@ -393,8 +393,7 @@ defmodule SimpleshopTheme.Theme.PreviewData do
     # Get available variants for pricing
     available_variants =
       product.variants
-      |> Enum.filter(& &1.is_enabled)
-      |> Enum.filter(& &1.is_available)
+      |> Enum.filter(&(&1.is_enabled and &1.is_available))
 
     # Get the cheapest available variant for display price
     cheapest_variant =