fix: Prevent GutenbergKit retain cycle

[dcalhoun]

Description

Close CMM-834.

It appears the strong Autosaver references and, possibly, lack of cleaning up asset loading tasks and view elements led to a retain cycle. The retain cycle prevented proper disposal of WebViews. The memory leak likely leads to performance degradations and crashes.

Testing instructions

1. Verify pending changes are persisted via autosave mechanism

1. Open the GutenbergKit editor for a new or existing post.
2. Make content changes—required to rigger autosaver.
3. Attempt saving changes as well as closing the editor with pending changes.
4. Verify new changes are persisted as expected.

2. Verify WebViews are disposed upon editor close

1. Open the GutenbergKit editor.
2. Insert content—required to rigger autosaver.
3. Close the editor and discard/save changes.
4. Repeat a few times.
5. Attempt to inspect the WebView via Safari developer tools.
6. Verify WebViews are not retained after the editor closes.

[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	29562
	Version	PR #24936
	Bundle ID	com.jetpack.alpha
	Commit	35a0f0c
	Installation URL	1j37can62algg

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 WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Configuration	Release-Alpha
	Build Number	29562
	Version	PR #24936
	Bundle ID	org.wordpress.alpha
	Commit	35a0f0c
	Installation URL	4reufcgd6eaf0

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

[Copilot]

Pull Request Overview

This PR fixes a memory leak in GutenbergKit by preventing a retain cycle that was preventing proper disposal of WebViews. The fix addresses strong reference cycles in the Autosaver and improves cleanup of view controllers and tasks during deinitialization.

• Changed Autosaver closure to use weak self reference to break retain cycle
• Added proper cleanup of loading tasks and child view controllers in deinit

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[sonarqubecloud]

Quality Gate passed

Issues
0 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

[kean]

Approving the "autosaver" part, but I've noticed a couple of issues with loading dependencies. For example, it cancels the loading when you open "Revisions", and it also shows an infinite spinner when the dependencies fail load. I'll open a PR addressing these.