Add manage folders E2E tests for mobile and desktop (BrowserStack)

[rwood-moz]

What changed?

Add E2E tests for managing folders in WebMail, and update the UI smoke test also.

Why?

Expand the current E2E test suite that runs in BrowserStack on desktop and mobile browsers.

Limitations and Notes

More specifically:

• Updated the smoke test to run regardless on if the inbox is empty or not at the test start (bug fix)
• Updated the smoke test to verify the settings dialog appears
• Updated the light/dark theme test (in the smoke test) to first turn off the 'follow system theme' option so that the switch theme/mode button appears
• Updated the smoke test to exercise the Manage Folders dialog controls (basic check only)
• Updated the smoke test for other recent app/locator changes
• Consolidated the UI smoke test into one test (no need to have separate tests for desktop and mobile)
• Added a new Manage Folders E2E test to actually add/modify/delete folders via the Manage Folders dialog
• Moving messages in/out of folders will be done in the separate Message Processing test in Add message processing E2E tests to run in BrowserStack #68
• Updated to the newest browserstack-node-sdk 1.67.0 I tested this out with these E2E tests in BrowserStack and it worked fine

I worked with Codex AI to make this patch. I reviewed all code changes and tested thoroughly.

Applicable Issues

Fixes #70.

QA Log

I ran the updated E2E tests (UI smoke test and the new folder management test):

• On my local machine on Firefox desktop ✅
• On my local machine on the Playwright android mobile viewport ✅
• On Firefox desktop in BrowserStack ✅
• On Chromium desktop in BrowserStack ✅
• On Safari desktop in BrowserStack ✅
• On Android Chrome on a Google Pixel 10 device in BrowserStack ✅

All tests pass.

[rwood-moz]

After the most recent Stormbox updates this new test no longer works. Moving back into WIP.

[rwood-moz]

After the most recent Stormbox updates this new test no longer works. Moving back into WIP.

Ok I've updated the new folder management test and the UI smoke test to work with the latest Webmail changes, and this patch is now ready for review.