Extract builder from app

Building is different from running

lib/tasks/mrsk/app.rake

@@ -2,28 +2,6 @@ require_relative "setup"
 
 namespace :mrsk do
   namespace :app do
-    desc "Deliver a newly built app image to servers"
-    task deliver: %i[ push pull ]
-
-    desc "Build locally and push app image to registry"
-    task :push do
-      run_locally do 
-        begin
-          info "Building multi-architecture images may take a while (run with VERBOSE=1 for progress logging)"
-          execute *MRSK.app.push
-        rescue SSHKit::Command::Failed => e
-          error "Missing compatible buildx builder, so creating a new one first"
-          execute *MRSK.app.create_new_builder
-          execute *MRSK.app.push
-        end
-      end unless ENV["VERSION"]
-    end
-
-    desc "Pull app image from the registry onto servers"
-    task :pull do
-      on(MRSK.config.hosts) { execute *MRSK.app.pull }
-    end
-
     desc "Run app on servers (or start them if they've already been run)"
     task :run do
       MRSK.config.roles.each do |role|