Add bare-bones Item Getting Guide page

TNT requested that we figure out ways to connect the dots between
people's intentions on DTI to their purchases in the NC Mall.

But rather than just slam ad links everywhere, our plan is to design an
actually useful feature about it: the "Item Getting Guide". It'll break
down items by how you can actually get them (NP economy, NC Mall,
retired NC, Dyeworks, etc), and we're planning some cute actions you
can take, like shortcuts for getting them onto trade wishlists or into
your NC Mall cart.

This is just a little demo version of the page, just breaking down
items specified in the URL into NC/NP/PB! Later we'll do more granular
breakdown than this, with more info and actions—and we'll also like,
link to it at all, which isn't the case yet! (The main way we expect
people to get here is by a "Get these items" button we'll add to the
outfit editor, but there might be other paths, too.)

app/assets/stylesheets/_items.sass

@@ -1,6 +1,6 @@
 @import "partials/campaign-progress"
 
-body.items, body.item_trades
+body.items-index, body.items-show, body.items-needed, body.item_trades
   +campaign-progress
 
   text-align: center

app/controllers/items_controller.rb

@@ -112,6 +112,22 @@ class ItemsController < ApplicationController
     end
   end
 
+  def sources
+    item_ids = params[:ids].split(",")
+    @items = Item.where(id: item_ids).order(:name)
+
+    if @items.empty?
+      render file: "public/404.html", status: :not_found, layout: nil
+      return
+    end
+
+    @nc_items = @items.select(&:nc?)
+    @np_items = @items.select(&:np?)
+    @pb_items = @items.select(&:pb?)
+
+    render layout: "application"
+  end
+
   protected
 
   def assign_closeted!

app/models/item.rb

@@ -158,6 +158,10 @@ class Item < ApplicationRecord
     I18n.with_locale(:en) { self.description == PAINTBRUSH_SET_DESCRIPTION }
   end
 
+  def np?
+    !nc? && !pb?
+  end
+
   def owned?
     @owned || false
   end

app/views/items/sources.html.haml

@@ -0,0 +1,14 @@
+- title "Item Getting Guide"
+%h1#title Item Getting Guide
+
+- if @nc_items.present?
+	%h2 Neocash items
+	= render @nc_items
+
+- if @np_items.present?
+	%h2 Neopoint items
+	= render @np_items
+
+- if @pb_items.present?
+	%h2 Paintbrush items
+	= render @pb_items

config/routes.rb

@@ -27,6 +27,7 @@ OpenneoImpressItems::Application.routes.draw do
 
     collection do
       get :needed
+      get "sources/:ids", action: :sources
     end
   end
   resources :species, only: [] do