Persist item user lists form open/closed state across pageloads

Using good ol'-fashioned cookies! The JS sets it, and then Rails reads
it on pageload. That way, there's no flash of content for it to load in
after JS loads.

app/assets/javascripts/items/item_header.js

@@ -1,10 +1,21 @@
+function setFormStateCookie(value) {
+	const thirtyDays = 60 * 60 * 24 * 30;
+	document.cookie = `DTIItemPageUserListsFormState=open;max-age=${thirtyDays}`;
+}
+
 const headers = document.querySelectorAll(".item-header");
 for (const header of headers) {
 	try {
 		const form = header.querySelector(".user-lists-form");
 		const opener = header.querySelector(".user-lists-form-opener");
 		opener.addEventListener("click", (event) => {
-			form.toggleAttribute("hidden");
+			if (form.hasAttribute("hidden")) {
+				form.removeAttribute("hidden");
+				setFormStateCookie("open");
+			} else {
+				form.setAttribute("hidden", "");
+				setFormStateCookie("closed");
+			}
 			event.preventDefault();
 		});
 	} catch (error) {

app/helpers/items_helper.rb

@@ -118,5 +118,9 @@ module ItemsHelper
     human_name = pet_type.species.name.humanize
     image_tag(src, :alt => human_name, :title => human_name)
   end
+
+  def item_header_user_lists_form_state
+    cookies.fetch("DTIItemPageUserListsFormState", "closed")
+  end
 end
 

app/views/items/_item_header.haml

@@ -36,7 +36,8 @@
           user_closet_hangers_path(current_user),
           class: 'user-lists-form-opener'
 
-  = form_tag update_quantities_user_item_closet_hangers_path(user_id: current_user, item_id: item), method: :put, class: 'user-lists-form', hidden: true do
+  - if user_signed_in?
+    = form_tag update_quantities_user_item_closet_hangers_path(user_id: current_user, item_id: item), method: :put, class: 'user-lists-form', hidden: item_header_user_lists_form_state != "open" do
       %h3
         = t 'items.show.closet_hangers.header_html',
           user_items_link: link_to(t('your_items'),