Improve settings UX and tests

[kiannidev]

Summary

• Enhance Privacy settings page with proper loading, error handling, and optimistic toggle for 'Help improve Eigent'.
• Improve General settings Network Proxy UX with helper copy, change detection, and restart flow.
• Add unit tests for Privacy and General settings pages to cover loading, validation, and save behavior.

[4pmtong]

Thanks @kiannidev for contribution! could @a7m-1st help review it?

[bytecii]

Can you give a screenshot for your UI changes?

[kiannidev]

Thanks for the review @bytecii . This PR primarily improves **settings behavior and reliability**, so visual UI changes are intentionally minimal.

What changed visually

• General → Network Proxy: added a small helper text line explaining proxy behavior.
• General → Network Proxy: improved button states:
  • Save is disabled until the value is changed.
  • After save, action changes to Restart to Apply.

What changed functionally (main scope)

• Privacy setting toggle now has stronger loading/save handling and rollback on save failure.
• Improved error handling for privacy/proxy fetch and save failures.
• Added broader unit test coverage for Privacy and General proxy flows.

[kiannidev]

Hi, @bytecii
I uploaded the image for a long time ago.
Please review it

[Douglasymlai]

Hi @kiannidev, thanks a lot for the contribution and for sticking with this through the merge conflicts — appreciate the effort here!

After review, we felt the proxy loading/disabled-state handling and the extra helper text are a bit redundant with the existing design (the Save-until-changed behavior already communicates the "no-op" state, and the helper text mostly repeats the existing description). We think a better approach would be adding a Reset button to the proxy setting, so users can quickly revert an in-progress edit back to the last-saved value — that would give a nicer UX win than the current changes.

We've opened a new issue for this, and you're very welcome to take it on if you're interested — happy to have you continue building on this work! #1728

Thanks again for the PR and the test coverage you added along the way.