Hydrates the zustand store with the user's persisted settings via
prop (SSR-correct, no flicker). Opens an EventSource to
/api/realtime/user-settings so changes from other tabs/devices
flow into the same store. Demo accounts skip the SSE subscription.
Layout now selects user.settings alongside the other user fields,
no extra DB roundtrip.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
