fix(portal): remove stray } in logo data URL and restore Dashboard redirect

- CustomerPortal.tsx: fix stray } in base64 data URL src attribute
- Dashboard.tsx: restore Navigate to /login for !sessionId (defense-in-depth)

The stray } was introduced in commit fa92a65 which also reverted
the Dashboard redirect. This commit restores both fixes.

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

apps/web/src/portal/CustomerPortal.tsx

@@ -260,7 +260,7 @@ export function CustomerPortal() {
           <div className="hidden md:flex items-center gap-3 px-6 py-5 border-b border-stone-100">
             {branding.logoBase64 && branding.logoMimeType ? (
               <img
-                src={`data:${branding.logoMimeType};base64,${branding.logoBase64}}`}
+                src={`data:${branding.logoMimeType};base64,${branding.logoBase64}`}
                 alt=""
                 className="w-10 h-10 rounded-xl object-contain"
               />

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();