fix(portal): redirect unauthenticated users to /login

CustomerPortal now redirects to /login after session init completes
with no valid session, preventing portal chrome from rendering for
unauthenticated users. Dashboard !sessionId branch uses Navigate
redirect instead of dead-end UI. Staff redirect in App.tsx verified.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/web/src/portal/sections/Dashboard.tsx

@@ -1,4 +1,5 @@
 import { useState, useEffect } from "react";
+import { Navigate } from "react-router-dom";
 import { Calendar, Clock, PawPrint, CreditCard, Star, ChevronRight, AlertTriangle } from "lucide-react";
 
 interface DashboardProps {
@@ -183,13 +184,7 @@ export function Dashboard({
   }
 
   if (!sessionId) {
-    return (
-      <div className="space-y-6">
-        <div className="bg-stone-100 rounded-2xl p-5 text-center">
-          <p className="text-stone-600">Please sign in to view your dashboard.</p>
-        </div>
-      </div>
-    );
+    return <Navigate to="/login" replace />;
   }
 
   const upcomingAppointments = getUpcomingAppointments();