refactor: Transition to authentication system and remove identity management

- Replace identity management with a new authentication system across the application.
- Update App.vue to integrate LoginDialog and remove PasswordDialog.
- Modify Navbar.vue to handle user authentication state and logout functionality.
- Enhance Home.vue to display user information upon login.
- Implement routing changes in index.ts to enforce authentication requirements for protected routes.

src/pages/Home.vue

@@ -2,26 +2,23 @@
   <div class="container py-8 space-y-6">
     <PWAInstallPrompt auto-show />
     <NotificationPermission auto-show />
-    <NostrFeed feed-type="announcements" />
+    
+    <!-- Welcome Section -->
+    <div class="text-center space-y-4">
+      <h1 class="text-3xl font-bold tracking-tight">Welcome back!</h1>
+      <p class="text-lg text-muted-foreground">
+        You are logged in as {{ auth.userDisplay.value?.name }}
+      </p>
+    </div>
+
+    <!-- User Profile Card -->
+    <UserProfile />
   </div>
 </template>
 
 <script setup lang="ts">
-import { onMounted } from 'vue'
-import NostrFeed from '@/components/nostr/NostrFeed.vue'
 import NotificationPermission from '@/components/notifications/NotificationPermission.vue'
 import PWAInstallPrompt from '@/components/pwa/PWAInstallPrompt.vue'
-import { useNostrFeedPreloader } from '@/composables/useNostrFeedPreloader'
-
-// Preload the announcements feed for better UX
-const feedPreloader = useNostrFeedPreloader({
-  feedType: 'announcements',
-  limit: 50,
-  includeReplies: false
-})
-
-onMounted(async () => {
-  // Auto-preload if we have stored data
-  await feedPreloader.autoPreload()
-})
+import UserProfile from '@/components/auth/UserProfile.vue'
+import { auth } from '@/composables/useAuth'
 </script>