fix(settings): keep experimental state consistent

[appergb]

Summary

• Centralize experimental labels across the settings UI and five locales.
• Prevent stale preference broadcasts from rolling back queued optimistic settings writes.
• Return backend-canonical preferences from set_settings before applying the final saved state.
• Carry the existing OpenLess 1.3.17 Cask update into the release branch.

Validation

• npm test

Notes

• Includes the existing chore(cask): update OpenLess to 1.3.17 commit from the merged feature branch.