Re-translate the Japanese version (#1871)

* Retranslate Japanese docs with GPT-5.4

* Retranslate Japanese code with GPT-5.4

ja/codes/ruby/test_all.rb

@@ -0,0 +1,23 @@
+require 'open3'
+
+start_time = Time.now
+ruby_code_dir = File.dirname(__FILE__)
+files = Dir.glob("#{ruby_code_dir}/chapter_*/*.rb")
+
+errors = []
+
+files.each do |file|
+  stdout, stderr, status = Open3.capture3("ruby #{file}")
+  errors << stderr unless status.success?
+end
+
+puts "\x1b[34mTested #{files.count} files\x1b[m"
+
+unless errors.empty?
+  puts "\x1b[33mFound exception in #{errors.length} files\x1b[m"
+  raise errors.join("\n\n")
+else
+  puts "\x1b[32mPASS\x1b[m"
+end
+
+puts "Testing finishes after #{((Time.now - start_time) * 1000).round} ms"