Reader: Update cells for iPad

[kean]

This PR tweaks the design of the cells a bit for iPad (see iOS-18 channel for more details) and fixes an issue where the app was adding the same constraints over and over again to the cells as you scroll. This is not exactly the target design, but is already an improvement that makes the list usable as opposed to the current production design.

To test:

Please, help run some more regression tests on iPhone.

Regression Notes

1. Potential unintended areas of impact

2. What I did to test those areas of impact (or what existing automated tests I relied on)

3. What automated tests I added (or what prevented me from doing so)

PR submission checklist:

• [ ] I have completed the Regression Notes.
• [ ] I have considered adding unit tests for my changes.
• [ ] I have considered adding accessibility improvements for my changes.
• [ ] I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

Testing checklist:

• [ ] WordPress.com sites and self-hosted Jetpack sites.
• [ ] Portrait and landscape orientations.
• [ ] Light and dark modes.
• [ ] Fonts: Larger, smaller and bold text.
• [ ] High contrast.
• [ ] VoiceOver.
• [ ] Languages with large words or with letters/accents not frequently used in English.
• [ ] Right-to-left languages. (Even if translation isn’t complete, formatting should still respect the right-to-left layout)
• [ ] iPhone and iPad.
• [ ] Multi-tasking: Split view and Slide over. (iPad)

[wpmobilebot]

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

	App Name	Jetpack Alpha
	Configuration	Release-Alpha
	Build Number	pr23575-2511782
	Version	25.3
	Bundle ID	com.jetpack.alpha
	Commit	251178269c2ff978a05bb3bc884e79d289cd499a
	App Center Build	jetpack-installable-builds #9670

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

[wpmobilebot]

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

	App Name	WordPress Alpha
	Configuration	Release-Alpha
	Build Number	pr23575-2511782
	Version	25.3
	Bundle ID	org.wordpress.alpha
	Commit	251178269c2ff978a05bb3bc884e79d289cd499a
	App Center Build	WPiOS - One-Offs #10627

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