Basic trade and holdings view (#1271)

* Add trade view

* Lint fix

* Fix stale placeholder variable

* Add holding view

app/models/security.rb

@@ -5,6 +5,12 @@ class Security < ApplicationRecord
 
   validates :ticker, presence: true, uniqueness: { case_sensitive: false }
 
+  def current_price
+    @current_price ||= Security::Price.find_price(ticker:, date: Date.current)
+    return nil if @current_price.nil?
+    Money.new(@current_price.price, @current_price.currency)
+  end
+
   private
 
     def upcase_ticker