RTC: Prevent controlled block synchronization from intercepting undo

[maxschmeling]

What?

This PR prevents entity-driven controlled block synchronization from adding derived changes to RTC undo history.

It also adds an end-to-end reproduction covering a post with a Navigation block where a delayed self-update previously intercepted a collaborator's first undo.

Follow-up to #78864.

Why?

RTC uses one global undo ordering across multiple Yjs documents. After a collaborator typed in the post body, the incoming round-trip update could cause the controlled Navigation block to emit a derived wp_navigation entity edit. That edit was tracked on a separate Yjs document and placed above the user's typing in the global undo stack.

As a result, pressing undo once popped an invisible Navigation update instead of removing the typed character. The feedback update could also clear redo.

How?

Controlled block setup, replacement, reset, and cleanup are already marked non-persistent because they reflect incoming entity state. This PR additionally marks those derived changes with history: 'ignore'.

useBlockSync already propagates that history mode as undoIgnore: true, so the derived Navigation update is excluded from Yjs undo history while direct user-authored Navigation edits remain tracked.

Testing Instructions

1. Start the test environment if needed: npm run wp-env-test start.

2. Run:

   RTC_WS_DELAY=50 npm run test:e2e:rtc-websocket -- test/e2e/specs/editor/collaboration/collaboration-undo-navigation-block.spec.ts

3. Confirm the test passes and the delayed User B Navigation edit is logged with undoIgnore=true.

4. Run the hook unit tests:

   npm run test:unit -- packages/block-editor/src/components/provider/test/use-block-sync.js

For a manual check, run RTC_WS_DELAY=50 npm run rtc:ws, open the same post in two administrator sessions, and include a Navigation block between paragraphs. Type one character in a paragraph as the second user, wait at least two seconds, and press undo once. The character should be removed and redo should remain available.

Testing Instructions for Keyboard

Follow the manual steps above and use the platform undo shortcut (Cmd+Z on macOS or Ctrl+Z elsewhere). The typed character should be removed with one shortcut press.

Screenshots or screencast

Not applicable; this changes undo-stack behavior without changing the UI.

Use of AI Tools

AI assistance: Yes
Tool: Codex
Used for: Investigating the RTC undo data flow, implementing the fix, running automated and manual verification, and drafting this description.

[github-actions]

Size Change: +13 B (0%)

Total Size: 7.75 MB

📦 View Changed

Filename	Size	Change
build/scripts/block-editor/index.min.js	428 kB	+13 B (0%)

_{compressed-size-action}

[github-actions]

Flaky tests detected in da96511.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/29944099202
📝 Reported issues:

• [Flaky Test] Should insert content using the global inserter #78924 in /test/e2e/specs/widgets/editing-widgets.spec.js
• [Flaky Test] Should navigate inner blocks with arrow keys #39607 in /test/e2e/specs/editor/various/writing-flow.spec.js
• [Flaky Test] should update the HTML only for the latest navigation #78835 in /test/e2e/specs/interactivity/router-navigate.spec.ts

[github-actions]

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Co-authored-by: alecgeatches <alecgeatches@git.wordpress.org>
Co-authored-by: maxschmeling <maxschmeling@git.wordpress.org>
Co-authored-by: ingeniumed <ingeniumed@git.wordpress.org>

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[ingeniumed]

Comments around the test need to be tweaked other LGTM