保留拼写确认按钮，同时新增键盘完成键提交

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

LearnEnglish/LearnEnglish/Views/SpellingInputView.swift

@@ -55,6 +55,7 @@ final class SpellingInputView: UIView, UITextFieldDelegate {
         hiddenField.autocapitalizationType = .none
         hiddenField.spellCheckingType = .no
         hiddenField.keyboardType = .asciiCapable
+        hiddenField.returnKeyType = .done
         hiddenField.frame = .zero
         addSubview(hiddenField)
 
@@ -178,6 +179,12 @@ final class SpellingInputView: UIView, UITextFieldDelegate {
         return false
     }
 
+    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
+        guard isComplete else { return false }
+        onSubmit?()
+        return false
+    }
+
     // MARK: - Boxes
 
     private func rebuildBoxes() {