Rails: update bin/ folder (#1601)

Delete old `bin/` stubs and add `pnpm install` to setup script.

Source: mockdeep/Rails-Template#1476

Co-authored-by: Template Bot <template-bot@users.noreply.github.com>

Author: rails-template-sync[bot]

bin/setup

@@ -17,6 +17,9 @@ FileUtils.chdir(APP_ROOT) do
   puts "== Installing dependencies =="
   system("bundle check") || system!("bundle install")
 
+  # Install JavaScript dependencies
+  system!("pnpm install")
+
   # puts "\n== Copying sample files =="
   # unless File.exist?("config/database.yml")
   #   FileUtils.cp "config/database.yml.sample", "config/database.yml"