feat: add telegram-style resource stream

src/components/messageStream/DaySeparator.tsx

@@ -0,0 +1,9 @@
+export function DaySeparator({ label }: { label: string }) {
+  return (
+    <div className="sticky top-[58px] z-[5] flex justify-center py-2">
+      <span className="rounded-full bg-ark-panel/80 px-3 py-1 text-xs text-neutral-300 backdrop-blur">
+        {label}
+      </span>
+    </div>
+  );
+}