Cross-browser verification of reply-form moves and scroll anchoring

Problem/Motivation

Element.moveBefore is Chromium-only, so Firefox and Safari fall back to disconnect/reconnect for reply-form moves, which is exactly where CKEditor state is at risk. WebKit also has no native scroll anchoring, and branch expansion relies on it. The browser suite is Chromium-only (tests/browser/playwright.config.js), and the docs state Firefox and WebKit were never tested. For a beta this deserves an explicit issue rather than a footnote.

Steps to reproduce

• Run the reply-form move and branch-expansion flows in Firefox and WebKit.
• Observe editor state risk on the move fallback and missing scroll anchoring.

Proposed resolution

• Verify the reply-form move fallback preserves editor state in Firefox and Safari.
• Provide scroll anchoring that does not rely on WebKit's missing native support.
• Extend the browser suite beyond Chromium.

Remaining tasks

• Run the suite in Firefox and WebKit and record results.

User interface changes

None; reliability in Firefox and Safari.

API changes

None anticipated.

Data model changes

None anticipated.

AI-Generated: Yes (Used Opus 5 and DeepSeek Flash to review and discover these issues)