[Woo POS] Finalise design of payment success screen for pos demo build

[joshheald]

Closes: #14063

Description

This PR updates the success screen in POS to match final designs:

• Use less bright green
• Restore the checkmark icon
• Remove the icon from the New Order button
• Fix the spacing and height of the New Order button

Additionally, I've updated the description for the menu item to the newly agreed string: Accept payments at your physical store

Designs

TfaZ4LUkEwEGrxfnEFzvJj-fi-2530_13218

Note that I have used posSecondaryBackground, not gutenbergGrey900, as we don't have the latter defined in the project and this screen should match the item list from the first screen.

Steps to reproduce

1. Launch the app and navigate to POS
2. Take a payment
3. Observe that the success screen matches designs

Testing information

No unit tests: UI changes only. I've tested this on an iPad running iOS 17

Screenshots

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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.

Reviewer (or Author, in the case of optional code reviews):

Please make sure these conditions are met before approving the PR, or request changes if the PR needs improvement:

• The PR is small and has a clear, single focus, or a valid explanation is provided in the description. If needed, please request to split it into smaller PRs.
• Ensure Adequate Unit Test Coverage: The changes are reasonably covered by unit tests or an explanation is provided in the PR description.
• Manual Testing: The author listed all the tests they ran, including smoke tests when needed (e.g., for refactorings). The reviewer confirmed that the PR works as expected on all devices (phone/tablet) and no regressions are added.

[joshheald]

@joe-keenan tagging you here, but don't worry about it if you don't have time, Gabriel's review is enough.

[wpmobilebot]

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

	App Name	WooCommerce iOS
	Build Number	pr14073-6becedf
	Version	20.6
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	6becedf
	App Center Build	WooCommerce - Prototype Builds #11059

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

[iamgabrielma]

Thanks for taking care of this. Changes look good in both light and dark mode 🚢

[joe-keenan]

Yep, looks good to me, too! Thanks for the last minute update!

(I want to remove the shadow on the check mark graphic, but it’s not a dealbreaker)