[jkmassel]

Description

Follow-up to #26327, from reviewing it.

Fixes two bugs in the plugin section web view and corrects one comment:

• "Watch on YouTube" did nothing. The player opens that link with window.open. This doesn't go through the navigation policy, and WebKit ignores it unless the web view has a uiDelegate. The Coordinator now implements createWebViewWith and opens the URL in the browser. The other links in the embed that use window.open get the same fix.
• Section text was invisible in dark mode. It was black on a dark background, because the page never opted in to dark mode and the web view is transparent. This is pre-existing. Adding color-scheme: light dark fixes it for every section.
• The baseURL comment said WebKit sends the plugin's page as the referrer. It sends only the origin (https://wordpress.org/). Confirmed by loading httpbin in an iframe.

	Before	After
Dark mode

What we left alone

• # links. With the base URL from Fix YouTube embeds in plugin descriptions #26327, these now open in the browser. This is correct: real links like #faq-header and #screenshots point at sections of the WordPress.org page, not at anything in the app's HTML. On trunk they did nothing.
• http:// images and iframes. The HTTPS base URL blocks them as mixed content. None of the 2,500 plugins we scanned use them.
• Third-party scripts running with the wordpress.org origin. We trust the WordPress.org filtering, and the app's cookie store had no wordpress.org cookies in our testing.

What I ran

• I built this change and ran the affected tests locally

WordPressTest/PluginInfoSectionContentTests: Test run with 3 tests in 1 suite passed

Without the CSS change, usesTheTextColorOfTheInterfaceStyle fails with dark → "rgb(0, 0, 0)".

The uiDelegate change has no unit test, because the Coordinator is private and the failure only shows up with a real window.open from the YouTube embed. It was checked in the app, below.

Testing instructions

Checked in Jetpack on an iPhone 18 Pro simulator (iOS 27.0), signed in to a local self-hosted site, with Page Generator installed:

• In dark mode, Description text is readable.
• Tapping "Watch on YouTube" opens the video in the browser. Before this change, it did nothing.
• In light mode, text is still black (covered by the test above).

Not checked: Vimeo embeds, and iPad.