fix: restore passive focus on full-block fields in Zelos

[minwookshin]

Fixed the missing passive focus outline on full-block fields in Zelos. Ran regression tests and reviewed the changes.

Fixes #10504.

AI assistance: OpenAI Codex (implementation and regression tests).

[github-actions]

Welcome! It looks like this is your first pull request in Blockly, so here are a couple of tips:

• You can find tips about contributing to Blockly and how to validate your changes on our developer site.
• We use conventional commits to make versioning the package easier. Make sure your commit message is in the proper format or learn how to fix it.
• If any of the other checks on this PR fail, you can click on them to learn why. It might be that your change caused a test failure, or that you need to double-check the style guide.
  Thank you for opening this PR! A member of the Blockly team will review it soon.

[mikeharv]

Hi Minwook! Thanks for submitting this fix. The change itself works, but I'm requesting a couple small changes before we can merge this.

• Use dom.addClass instead of this.fieldGroup_.classList.add(...). The rest of Field uses the helper already, including in initView() a few lines below.
• The AI generated tests are a little too padded for what this change is. I think we can cut the test down to a single full-block case. It would be good if we could do this without depending on the exact 5px 3px values.

Please re-tag me for review when you'd like me to take another look.

[mikeharv]

Thanks for making those changes. Instead of creating a brand new test file, could we add this new test to a new or existing suite in keyboard_navigation_test.ts?

[minwookshin]

Moved the test to keyboard_navigation_test.ts and reran the tests. @mikeharv, could you take another look?