Add steps to cards

app/views/cards/_card.json.jbuilder

@@ -1,5 +1,5 @@
 json.cache! [ card, card.column&.color ] do
-  json.(card, :id, :title, :status)
+  json.(card, :id, :number, :title, :status)
   json.description card.description.to_plain_text
   json.description_html card.description.to_s
   json.image_url card.image.presence && url_for(card.image)

app/views/cards/show.json.jbuilder

@@ -1 +1,7 @@
 json.partial! "cards/card", card: @card
+
+json.steps do
+  json.array! @card.steps do |step|
+    json.partial! "steps/step", step: step
+  end
+end