分隔线改为 1 物理像素发丝线，修复 UIScreen.main 弃用警告

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

LearnEnglish/LearnEnglish/Views/HairlineView.swift

@@ -0,0 +1,23 @@
+import UIKit
+
+final class HairlineView: UIView {
+    private var heightConstraint: NSLayoutConstraint?
+
+    override init(frame: CGRect) {
+        super.init(frame: frame)
+        backgroundColor = .separator
+        translatesAutoresizingMaskIntoConstraints = false
+        let constraint = heightAnchor.constraint(equalToConstant: 0.5)
+        constraint.isActive = true
+        heightConstraint = constraint
+    }
+
+    @available(*, unavailable)
+    required init?(coder: NSCoder) { fatalError() }
+
+    override func didMoveToWindow() {
+        super.didMoveToWindow()
+        let scale = window?.windowScene?.screen.scale ?? 2
+        heightConstraint?.constant = 1.0 / scale
+    }
+}

LearnEnglish/LearnEnglish/Views/QuizResultView.swift

@@ -133,10 +133,7 @@ final class QuizResultView: UIView {
             }, for: .touchUpInside)
             section.addArrangedSubview(button)
 
-            let divider = UIView()
+            let divider = HairlineView()
-            divider.backgroundColor = .separator
-            divider.translatesAutoresizingMaskIntoConstraints = false
-            divider.heightAnchor.constraint(equalToConstant: 1.0 / UIScreen.main.scale).isActive = true
             section.addArrangedSubview(divider)
         }
         return section

LearnEnglish/LearnEnglish/Views/WordDetailViewController.swift

@@ -106,10 +106,7 @@ final class WordDetailViewController: UIViewController {
         meaningLabel.font = .preferredFont(forTextStyle: .title2)
         meaningLabel.numberOfLines = 0
 
-        let divider = UIView()
+        let divider = HairlineView()
-        divider.backgroundColor = .separator
-        divider.translatesAutoresizingMaskIntoConstraints = false
-        divider.heightAnchor.constraint(equalToConstant: 1.0 / UIScreen.main.scale).isActive = true
 
         let exampleTitle = makeCaption("例句")
         let exampleLabel = UILabel()