[Order Creation - Taxes] Fix Scroll View in Tax Modal

[toupper]

Description

This PR fixes a visual issue in the TaxEducationalDialogView where the modal's corners were displayed incorrectly due to the ScrollView being the outermost container. This caused the background and corner radius to misbehave—specifically, the bottom corners appeared square until the content was scrolled.

The solution involves moving the styled container (VStack with background and corner radius) outside the ScrollView, ensuring the modal frame is preserved regardless of scroll interaction. The GeometryReader is not necessary, and this removed.

Steps to reproduce

With an increased device font size and a tax rate set in the settings of your store

1. Go to Orders
2. Tap on + to create a new order
3. Add a product
4. Tap on Set New Tax Rate
5. Tap on the ? button
6. The content should be scrollable. Before, the bottom corners appear square initially and become rounded only after scrolling. Now it is rounded.

Testing information

Tested on iPad with Largest accessibility siw

Screenshots

ScreenRecording_08-07-2025.17-11-08_1.MP4

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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.

[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	pr15997-ab1ea36
	Version	22.9
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	ab1ea36
	Installation URL	18s709rjsge9o

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

[joshheald]

Works as expected, thanks for improving this