Move device ID logic from @multica/store (Zustand persist) into a
simple useDeviceId hook in the web app. SSR returns empty string,
client reads/writes localStorage directly — no hydration mismatch,
no suppressHydrationWarning needed.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Use CSS mask-image gradients to hint at scrollable overflow in the chat
area. Adds useScrollFade hook that dynamically applies top/bottom fade
based on scroll position via scroll events and ResizeObserver.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Zustand persist generates a new deviceId on the server (no localStorage),
then hydrates a different value from localStorage on the client. Add
suppressHydrationWarning to the deviceId span since this mismatch is expected.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>