Frontend redesign chunk 6: Live view

New components/LiveView.tsx renders the default landing at "/": full-bleed
MapView (rail + legend from chunk 5) plus a new TimeScrubber strip below
it — real call-density bars over the selected 1h/6h/24h/7d window, tinted
by the worst severity in each bucket, playhead pinned to NOW. The playhead
doesn't scrub yet; that needs `resolved_at` on incidents, which doesn't
exist server-side (blocked chunk 13, in DEFERRED.md) — the density data
itself is live, not a fixture.

Distinguishes the two empty states UI_REDESIGN.md §4 calls out: a
configured-but-quiet org (nodes online, zero active incidents) now shows
"Listening — last check-in Xm ago" instead of rendering nothing, separate
from the zero-node case (chunk 10's Activation screen).

app/page.tsx's HomePage now renders LiveView directly for a signed-in,
provisioned user instead of the chunk-4 interim redirect to /incidents.

Per UI_REDESIGN.md chunk 6.

drb-frontend/app/page.tsx

@@ -1,13 +1,12 @@
 "use client";
 
-import { useEffect } from "react";
 import Link from "next/link";
-import { useRouter } from "next/navigation";
 import { LinkButton } from "@/components/ui/Button";
 import { Card } from "@/components/ui/Card";
 import { Badge } from "@/components/ui/Badge";
 import { PLANS } from "@/lib/billing";
 import { useAuth } from "@/components/AuthProvider";
+import { LiveView } from "@/components/LiveView";
 
 const CAPABILITIES = [
   {
@@ -147,21 +146,15 @@ function MarketingHomePage() {
 
 /**
  * "/" is marketing for a signed-out visitor and Live (the map) for anyone
- * signed in — see UI_REDESIGN.md §3, "the map is the home screen". The Live
- * screen itself lands in chunk 6; until then a signed-in, provisioned user
- * is sent to /incidents rather than shown stale marketing copy. A user with
- * no org_id yet still sees marketing (unchanged — that's the pre-redesign
- * behaviour for an unprovisioned account, out of scope here).
+ * signed in — see UI_REDESIGN.md §3, "the map is the home screen". A user
+ * with no org_id yet still sees marketing (unchanged — that's the
+ * pre-redesign behaviour for an unprovisioned account, out of scope here;
+ * ChromeSwitcher's own no-claim guard only fires off marketing paths).
  */
 export default function HomePage() {
   const { user, loading, orgId } = useAuth();
-  const router = useRouter();
 
-  useEffect(() => {
-    if (loading || !user || !orgId) return;
-    router.replace("/incidents");
-  }, [loading, user, orgId, router]);
-
-  if (loading || (user && orgId)) return null;
+  if (loading) return null;
+  if (user && orgId) return <LiveView />;
   return <MarketingHomePage />;
 }