学习模式确认后保持键盘不消失

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

LearnEnglish/LearnEnglish/Views/QuizViewController.swift

@@ -359,7 +359,11 @@ final class QuizViewController: UIViewController {
             wrongWords.append(question.word)
         }
         correct ? Haptics.correct() : Haptics.wrong()
+        if config.isStudyMode {
+            spellingView.freezeInput()
+        } else {
             spellingView.deactivate()
+        }
         spellingView.showResultState(correct: correct)
         showResult(correct, for: question)
     }

LearnEnglish/LearnEnglish/Views/SpellingInputView.swift

@@ -122,6 +122,11 @@ final class SpellingInputView: UIView, UITextFieldDelegate {
         refreshBoxes()
     }
 
+    func freezeInput() {
+        inputEnabled = false
+        refreshBoxes()
+    }
+
     func showResultState(correct: Bool) {
         let color = correct ? Theme.Color.correct : Theme.Color.wrong
         for position in blankPositions {