implement alternative match-making approach with Lua scripts in Redis

main-server/config/routes.rb

@@ -1,12 +1,16 @@
 Rails.application.routes.draw do
+  mount ActionCable.server => "/cable"
+
   namespace :api do
     post   "register", to: "registrations#create"
     post   "login",    to: "sessions#create"
     delete "logout",   to: "sessions#destroy"
     get    "me",       to: "sessions#me"
 
-    post   "matchmaking", to: "matchmaking#create"
     delete "matchmaking", to: "matchmaking#destroy"
+
+  # Matchmaking starts over the MatchmakingChannel WebSocket
+  # (see app/channels/matchmaking_channel.rb).
   end
 
   # Reveal health status on /up that returns 200 if the app boots with no exceptions, otherwise 500.