style: correct string split style

- Change string split method from single quotes to double quotes.

This commit improves code consistency by aligning the string
split syntax with the rest of the codebase. No functional
changes were made as a result of this update.

app/controllers/application_controller.rb

@@ -102,7 +102,7 @@ class ApplicationController < ActionController::Base
     return locale if available_locales.include?(locale)
 
     # 尝试基础语言匹配（例如：当请求 'zh' 时匹配 'zh-CN'）
-    base_language = locale.split('-').first
+    base_language = locale.split("-").first
     matching_locale = available_locales.find do |available_locale|
       available_locale.start_with?(base_language)
     end