[Bug] [iOS] App delegate swizzler has no UIScene equivalent — cold-launch & universal links miss Analytics/Dynamic Links on scene-based apps

从 app/src/invites/ios/invites_ios_startup.mm 开始，阅读 RunOnAppDelegateClasses 和 HookAppDelegateMethods，以及列出的 UIApplicationDelegate hooks。跟踪 issue 中描述的 scene delegate 传递路径，并确定如何在保留原始实现的同时让覆盖范围触达 Dynamic Links 和 Analytics；完成的标准是，报告中的 cold-launch 和已连接 scene 的 URL 及 user-activity 路径不再被静默丢弃。

Environment

• Platform: iOS (scene-based lifecycle, UIWindowSceneDelegate)
• Firebase C++ SDK version: (also consumed via Firebase Unity SDK 12.10.1)
• Installed via: Unity (FirebaseCppApp / FirebaseCppAnalytics), with FirebaseAnalytics/FirebaseCore pods 11.14.0, GoogleUtilities 8.1.2
• Relevant products: Analytics (campaign attribution)

Problem Description

The C++ SDK's iOS app-delegate swizzler (app/src/invites/ios/invites_ios_startup.mm, hooking installed via +load → RunOnAppDelegateClasses → HookAppDelegateMethods) only replaces UIApplicationDelegate methods:

• application:openURL:options:
• application:openURL:sourceApplication:annotation:
• application:continueUserActivity:restorationHandler:
• applicationDidBecomeActive:

There is no UISceneDelegate/UIWIndowSceneDelegate handling anywhere in the C++ SDK (looking at unity-v12.10.1 and v13.10.0)

On modern scene-based apps (UIWindowSceneDelegate), URL/NSUserActivity delivery moves off the app delegate onto the scene delegate. The C++ SDK adds nothing on top. As a result these link-delivery paths reach neither the C++ Dynamic Links machinery nor Analytics:

• scene:willConnectToSession:options: — cold-launch deep links (connectionOptions.URLContexts) and cold-launch universal links (connectionOptions.userActivities)
• scene:openURLContexts: — deep links delivered while the scene is already connected
• scene:continueUserActivity: — universal links delivered while the scene is already connected

Impact: on scene-based iOS apps, cold-launch deep/universal links and connected-scene universal links are silently dropped by the SDK.

Steps to reproduce:

1. Scene-based iOS app (Unity export uses UnityScene : UIWindowSceneDelegate in their latest Editor versions).
2. Register a Dynamic Link / campaign URL.
3. Cold-launch the app via a universal link → delivered to scene:willConnectToSession:options:.
4. Observe: no firebase::/GUL frame in the stack for that delivery; no Dynamic Link resolution; no Analytics campaign event. (Same for scene:continueUserActivity: or scene:openURLContexts: while connected.)

Question for maintainers:

• Is scene-delegate support planned for the C++ SDK's swizzler?

Workaround we're using (and would like validated):

We swizzle only the three uncovered scene methods on the scene delegate and forward to [FIRAnalytics handleOpenURL:] / [FIRAnalytics handleUserActivity:], chaining to the original implementation so the engine's own deep-link handling is preserved. Is this the recommended approach, and is there any double-handling risk if the SDK later completes scene coverage?