单词详情页增加学习按钮，支持单词拼写循环练习

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

LearnEnglish/LearnEnglish/Models/Quiz.swift

@@ -14,6 +14,13 @@ struct QuizSetupRequest: Hashable {
 struct QuizConfig: Hashable {
     let mode: QuizMode
     let words: [Word]
+    let isStudyMode: Bool
+
+    init(mode: QuizMode, words: [Word], isStudyMode: Bool = false) {
+        self.mode = mode
+        self.words = words
+        self.isStudyMode = isStudyMode
+    }
 }
 
 struct QuizQuestion: Identifiable {

LearnEnglish/LearnEnglish/Views/QuizViewController.swift

@@ -347,10 +347,23 @@ final class QuizViewController: UIViewController {
         resultLabel.textColor = correct ? Theme.Color.correct : Theme.Color.wrong
         resultLabel.isHidden = false
 
+        if config.isStudyMode {
+            if correct {
+                nextButton.isHidden = true
+                DispatchQueue.main.asyncAfter(deadline: .now() + 0.8) { [weak self] in
+                    self?.restart()
+                }
+            } else {
+                nextButton.configuration?.title = "继续学习"
+                nextButton.isEnabled = true
+                nextButton.isHidden = false
+            }
+        } else {
             nextButton.configuration?.title = currentIndex + 1 < questions.count ? "下一题" : "查看成绩"
             nextButton.isEnabled = true
             nextButton.isHidden = false
         }
+    }
 
     @objc private func speakCurrentWord() {
         guard let question = current else { return }
@@ -358,7 +371,9 @@ final class QuizViewController: UIViewController {
     }
 
     private func primaryButtonTapped() {
-        if config.mode == .spelling, selectedOption == nil {
+        if config.isStudyMode, selectedOption != nil {
+            restart()
+        } else if config.mode == .spelling, selectedOption == nil {
             guard let question = current, spellingView.isComplete else { return }
             submitSpelling(spellingView.typedWord(), for: question)
         } else if config.mode == .dictation, selectedOption == nil {

LearnEnglish/LearnEnglish/Views/WordDetailViewController.swift

@@ -31,6 +31,7 @@ final class WordDetailViewController: UIViewController {
         view.backgroundColor = .systemBackground
         title = categoryName
         navigationItem.largeTitleDisplayMode = .never
+        navigationItem.rightBarButtonItem = UIBarButtonItem(title: "学习", style: .plain, target: self, action: #selector(startSpelling))
         buildLayout()
         updateSpeakState()
         speechObserver = NotificationCenter.default.addObserver(
@@ -186,6 +187,12 @@ final class WordDetailViewController: UIViewController {
         return card
     }
 
+    @objc private func startSpelling() {
+        Haptics.selection()
+        let config = QuizConfig(mode: .spelling, words: [word])
+        navigationController?.pushViewController(QuizViewController(config: config), animated: true)
+    }
+
     private func searchMeaning() {
         Haptics.selection()
         let text = "\(word.meaning) 是什么意思"