feat: Wire up brand kit — favicon, logos, and hero mark across all layouts

Copies brand assets to frontend/public (favicon.png, logo.png, logo-hero.png).
Updates index.html, LoginView, RegisterView, DashboardLayout sidebar, and
PublicLayout footer with proper branding.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/layout/DashboardLayout.vue

@@ -59,8 +59,13 @@ function handleLogout() {
     <aside class="w-64 bg-neutral-900 border-r border-neutral-800 flex flex-col">
       <!-- Logo -->
       <div class="p-4 border-b border-neutral-800">
-        <h1 class="text-xl font-bold text-red-500 tracking-wider">CORROSION</h1>
-        <p class="text-xs text-neutral-500 mt-1">{{ auth.license?.server_name || 'Server Management' }}</p>
+        <div class="flex items-center gap-3">
+          <img src="/logo.png" alt="Corrosion" class="h-8 w-8" />
+          <div>
+            <h1 class="text-sm font-bold text-red-500 tracking-wider">CORROSION</h1>
+            <p class="text-xs text-neutral-500">{{ auth.license?.server_name || 'Server Management' }}</p>
+          </div>
+        </div>
       </div>
 
       <!-- Server Status Indicator -->

frontend/src/components/layout/PublicLayout.vue

@@ -7,7 +7,10 @@ import { RouterView } from 'vue-router'
     <RouterView />
 
     <footer class="py-6 text-center text-neutral-600 text-sm border-t border-neutral-800">
-      Powered by <span class="text-red-500 font-semibold">Corrosion</span>
+      <div class="flex items-center justify-center gap-2">
+        <img src="/logo.png" alt="Corrosion" class="h-4 w-4 opacity-60" />
+        <span>Powered by <span class="text-red-500 font-semibold">Corrosion</span></span>
+      </div>
     </footer>
   </div>
 </template>