释义搜索改用英文单词关键词，减少广告干扰

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

LearnEnglish/LearnEnglish/Views/WordDetailViewController.swift

@@ -188,7 +188,8 @@ final class WordDetailViewController: UIViewController {
 
     private func searchMeaning() {
         Haptics.selection()
-        guard let query = word.meaning.addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed),
+        let text = "\(word.word) 是什么意思"
+        guard let query = text.addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed),
               let url = URL(string: "https://www.google.com/search?q=\(query)") else { return }
         present(SFSafariViewController(url: url), animated: true)
     }