no issue

Browser tests were depending on the Ember build of Admin but that no longer matches reality since `adminForward` was made GA meaning the tests aren't testing what our users are seeing.

- swapped the ember build for the react build in the nx dependency graph for browser builds so we render the real-world React+Ember mix and Ember's `inAdminForward` feature flag correctly matches
- fixed test selectors to match the React sidebar

no issue

`networkidle` is unreliable with the React admin which makes many
additional API calls, preventing the network from settling. Replaced
with targeted element-based waits that are more deterministic.

no issue

The 2FA invite test no longer tests 2FA (it was disabled in test
config since staff device verification became a default setting).
The clearCookies() call was left over from the old 2FA setup and
caused session issues that the goto('/ghost') reload couldn't
reliably fix. Aligning with the non-2FA test pattern.

Ref
https://linear.app/ghost/issue/DES-1289/slack-domain-name-in-staff-settings-is-hardcoded-to-examplecom

We'd previously just use example.com to create the slug. Updated that to
use the site's URL instead.

| Before | After |
|--------|--------|
| <img width="288" height="120" alt="Screenshot 2026-02-16 at 15 14 45"
src="https://github.com/user-attachments/assets/13721575-fffa-4667-ad20-36a27e4c29aa"
/> | <img width="275" height="115" alt="Screenshot 2026-02-16 at 15 14
23"
src="https://github.com/user-attachments/assets/b38488d4-c74f-4e9f-957c-385ca6d40ee2"
/> |

This test-only change should have no user impact.

We had various calls like `should(actual).eql(expected)` and similar.
This replaces all of them with calls to `node:assert`, or wrappers
around that.

`git grep -F 'should('` returns no results after this change.

This change should have no user impact.

`value.should.be.an.Array()` has been replaced with `node:assert` in our
effort to replace Should.js with `node:assert`.

This test-only change should have no user impact. It removes:

- `should.ok`
- `should.fail`
- `should.notEqual`
- `should.not.exist`

`git grep -F ' should.'` returns no results after this change.