refactor: Use GutenbergKit configuration builder

[dcalhoun]

Description

Adopt the latest patterns for embracing immutable configuration introduced in wordpress-mobile/GutenbergKit#146.

Testing instructions

Smoke test editor functionality dependent upon configuration—theme styles, media uploads, remote editor (plugins), etc.

[sonarqubecloud]

Quality Gate passed

Issues
7 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[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	29081
	Version	PR #24662
	Bundle ID	org.wordpress.alpha
	Commit	90a32af
	Installation URL	23nbinuv6sjb8

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

[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	29081
	Version	PR #24662
	Bundle ID	com.jetpack.alpha
	Commit	90a32af
	Installation URL	1ipv6c1e0kh2g

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

[dcalhoun]

@jkmassel when testing the prototype build, I noted the theme styles were not loaded when I had the Experimental Block Editor Styles feature enabled. When I built this branch locally in Xcode 26 RC, I encountered a crash (image below) in the editor settings request logic. I imagine the crash/failed request explains the absence of theme styles (and rest of the editor settings).

Xcode crash

Do you encounter this? What might be occurring?

[jkmassel]

The crash is addressed in 45ba29d – it mostly shouldn't happen in production, that's the Core Data thread sanitizer complaining that we're accessing a Core Data object on the wrong thread. I reworked the initialization of that service to resolve it.

The root cause is likely that I removed @MainActor from fetchSettingsFromAPI in cfc5d97. That annotation was keeping all access to self.blog on the main thread, at the cost of interrupting the main thread to dispatch the HTTP request (which isn't ideal).

I'd be a little bit surprised if this was the cause of the missing theme styles, but it's possible.

[dcalhoun]

LGTM. The latest changes tested well for me.

I noted we no longer set the post ID and type. We should likely reinstate setting those. Other than that, we just need a PR approval from someone other than me as the PR author.

[dcalhoun]

Latest changes look good to me, tested well too.

I integrated a new GBK prerelease tag. This is ready for approval and merge by someone other than me (the PR author).

[sonarqubecloud]

Quality Gate passed

Issues
11 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud