fix(dashboard): Home page crashed when latest_video.top_tickers undefined

/api/meet-kevin/dashboard returns a latest_video summary that doesn't
include top_tickers (only the list endpoint does). Calling .slice()
on undefined crashed the whole page. Guard with ?? [] so the chip
row simply renders empty when the dashboard endpoint hasn't enriched
the latest video yet.

dashboard/src/pages/meetKevin/Home.tsx

@@ -118,7 +118,7 @@ export default function MeetKevinHome() {
                       {video.outlook}
                     </span>
                   )}
-                  {video.top_tickers.slice(0, 5).map((t) => (
+                  {(video.top_tickers ?? []).slice(0, 5).map((t) => (
                     <span
                       key={t.symbol}
                       title={`${t.action} · conviction ${Math.round(t.conviction * 100)}%`}