Render blog details with a native SwiftUI list

[crazytonyli]

Note

This PR will be merged after 27.3 code freeze, to give us a bit more time to test the changes during development.

Description

This prepares the site menu for SwiftUI destinations while keeping BlogDetailsViewController as the UIKit entry point.

1. Replace the table view with a native List, including sidebar selection, badges, and section styling.
2. Move the site header and pull-to-refresh into the list. The existing UIKit header and cards are embedded in SwiftUI.

Existing menu destinations retain UIKit routing. Native SwiftUI navigation for Comments follows in a separate PR.

Scrolling the site menu in My Site no longer reveals the navigation-bar title. Dashboard behavior is unchanged.

Testing instructions

• Switch between the dashboard and site menu. Check the header, scrolling, and pull-to-refresh.
• Scroll the site menu and confirm that the navigation-bar title stays hidden. On the dashboard, confirm that scrolling still reveals it.
• Switch sites and open Posts, Pages, Comments, and pinned custom post types.
• On iPad, check sidebar selection and detail-column navigation.
• Check card sizing and row layout with large text.

[dangermattic]

	1 Warning
⚠️	This PR is larger than 500 lines of changes. Please consider splitting it into smaller PRs for easier and faster reviews.

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[wpmobilebot]

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

	App Name	WordPress
	Configuration	Release-Alpha
	Build Number	34492
	Version	PR #26026
	Bundle ID	org.wordpress.alpha
	Commit	781d86d
	Installation URL	5v2b7p5aa2mb0

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[wpmobilebot]

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

	App Name	Jetpack
	Configuration	Release-Alpha
	Build Number	34492
	Version	PR #26026
	Bundle ID	com.jetpack.alpha
	Commit	781d86d
	Installation URL	7tr7p84432ct8

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

[crazytonyli]

This is an intentional change. When the blog details is displayed standalone on WordPress, we no longer show or hide the navigation bar depending on scrolling positions. Toggling navigation bar messes with SwiftUI list and results in very confusing list jumps. I decided to remove the toggling, instead of working around the jumps.

[crazytonyli]

Another small UI change: the header and footer now uses the default system layout, which has slightly large spacing than the old UIKit implementation. I think that's acceptable.