Fix TabBar icon assets and simplify Podfile post_install.

Rename tab icons to snake_case with @2x/@3x scales, register CYL plus button at app launch, and remove redundant Podfile hooks already covered by the Xcode project.

Co-authored-by: Cursor <cursoragent@cursor.com>

suixinkan_ios/SceneDelegate.swift

@@ -6,6 +6,7 @@
 //
 
 import UIKit
+import CYLTabBarController
 
 /// 窗口 Scene 代理，负责创建根窗口并挂载会话协调器。
 class SceneDelegate: UIResponder, UIWindowSceneDelegate {
@@ -23,6 +24,8 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
     ) {
         guard let windowScene = scene as? UIWindowScene else { return }
 
+        MainScanPlusButton.register()
+
         AppUITestLaunchState.resetIfNeeded()
 
         let rootViewController = RootViewController()