feat: add new pages and layout components for improved navigation and structure

- Added AppLayout component to standardize page layout with breadcrumb support.
- Introduced AppSidebar for navigation with user-specific links and admin options.
- Created new pages: SoundsPage, PlaylistsPage, ExtractionsPage, UsersPage, and SettingsPage.
- Removed obsolete SocketStatus component and replaced it with SocketBadge for connection status.
- Updated DashboardPage to utilize the new layout and sidebar components.
- Added NavGroup and NavItem components for better organization of sidebar navigation.
- Included SocketBadge to display real-time connection status.
- Updated package.json to include vitest and coverage-v8 for testing and coverage reporting.

src/pages/admin/SettingsPage.tsx

@@ -0,0 +1,22 @@
+import { AppLayout } from '@/components/AppLayout'
+
+export function SettingsPage() {
+  return (
+    <AppLayout 
+      breadcrumb={{
+        items: [
+          { label: 'Dashboard', href: '/' },
+          { label: 'Admin' },
+          { label: 'Settings' }
+        ]
+      }}
+    >
+      <div className="flex-1 rounded-xl bg-muted/50 p-4">
+        <h1 className="text-2xl font-bold mb-4">System Settings</h1>
+        <p className="text-muted-foreground">
+          System administration interface coming soon...
+        </p>
+      </div>
+    </AppLayout>
+  )
+}