drop all synthesis wording + sources box; 3->6 paragraphs, deeper prompt, 1.6k tok

src/app/page.tsx

@@ -121,7 +121,7 @@ function EmptyState() {
       <p className="mx-auto mt-2 max-w-md text-sm text-ink-500">
         The ingestion worker has not published anything yet. Trigger your first
         run (see the README “First run” section) and this page will fill with
-        synthesized briefings.
+        fresh briefings.
       </p>
     </div>
   );