fix(appearance): 完善深色模式和阅读页面对比度

- 区分按钮填充与图标颜色，统一书架、书源、搜索和阅读设置的选中态
- 调整编辑器语法高亮、键盘工具栏及统计卡片的浅深色显示
- 适配 RSS 正文和登录网页背景，保留书源自定义样式和页面状态
- 补充外观切换、页面对比度和管理页面的回归测试

App/Compatibility.swift

@@ -340,6 +340,22 @@ extension View {
         }
     }
 
+    @ViewBuilder
+    func readingNavigationBarBackground() -> some View {
+        if #available(iOS 16.0, *), !ReadingCompatibility.usesLegacyUI {
+            toolbarBackground(ReadingTheme.canvas, for: .navigationBar)
+                .toolbarBackground(.visible, for: .navigationBar)
+        } else {
+            background(ReadingUIKitConfiguration { controller in
+                let appearance = UINavigationBarAppearance()
+                appearance.configureWithOpaqueBackground()
+                appearance.backgroundColor = UIColor(ReadingTheme.canvas)
+                controller.navigationController?.navigationBar.standardAppearance = appearance
+                controller.navigationController?.navigationBar.scrollEdgeAppearance = appearance
+            })
+        }
+    }
+
     @ViewBuilder
     func readingTabBarBackground() -> some View {
         if #available(iOS 16.0, *), !ReadingCompatibility.usesLegacyUI {