Umbrella for Phase 0 of Plan: a very secure browser in Seed. The web pane stays behind the experiment flag until every task below is done. Tasks:

Secure browser: the daemon authenticates the desktop app

Secure browser: supported Electron with a lag policy and kill switch

Secure browser: harden the app window and start the hostile page suite

Secure browser: fuses, entitlements and signed update manifests

Secure browser: move the web pane to WebContentsView