iPad: Fix split view not working after the initial launch

[staskus]

WOOMOB-1009

Description

When the Woo app is initially launched and user logs in, Orders and Products tab are not displayed in a split view. The app needs to be killed and relaunched for a split view to appeared.

The iPadOS 18 + Xcode 16 hack was not working properly on first launch after login because it requires view.window to be available to access the window's trait collection. It turns all the views into .compact, not just the tab bar itself.

During initial login flow:

1. viewDidLoad() is called before tab controller is added to window hierarchy
2. AppCoordinator.displayLoggedInUI() sets tab controller as window root
3. view.window becomes available, but fixTabBarTraitCollectionOnIpadForiOS18 was already called when window was nil

Fixed by adding fixTabBarTraitCollectionOnIpadForiOS18() call to viewDidAppear() which is guaranteed to run after the view controller is in the window hierarchy and view.window is available.

Steps to reproduce

1. Remove the app
2. Install the app on the iPad
3. Login
4. Open Orders or Products tab
5. Confirm they appear in the split view

Testing information

Tested on iPad Air 18.5 simulator and iPadAir 26 device

Screenshots

Simulator.Screen.Recording.-.iPad.Air.11-inch.M3.-.2025-08-06.at.20.39.54.mov

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• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 23.0. This milestone is due in less than 2 days. Please make sure to get it merged by then or assign it to a milestone with a later deadline.

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[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce iOS Prototype by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce iOS Prototype
	Build Number	pr15985-82f9cd1
	Version	22.9
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	82f9cd1
	Installation URL	58tlqsn5s76jg

Automatticians: You can use our internal self-serve MC tool to give yourself access to those builds if needed.

[jaclync]

Thanks for fixing this, tested in iPad Air 13in iOS 18.5 simulator