- updateCheckService: gate the external request on `update_check_enabled`
(default on); when off, no network call, returns { disabled: true }
- aboutAdmin: GET/PUT /update-check-setting (admin-only) to toggle it
- StatusPage: a Switch on the admin System Status card to enable/disable
- privacy.js: state that an admin can disable it (was called "optional" with
no actual opt-out)
- tests/updateCheckOptOut.test.js: proves no external fetch when disabled
- docs: archive QA-B16-01, B16 ✅
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>