Refactor registration and dashboard features to support invite codes and Bunny uploads

- Moved registration logic to a new client component for better separation of concerns.
- Integrated invite code requirement based on feature flags in the registration process.
- Enhanced dashboard functionality to conditionally enable Bunny uploads based on feature flags.
- Updated various components and API routes to check for Bunny uploads and Stripe billing feature flags.
- Added new feature flag utilities for managing feature toggles in the application.

app/admin/page.tsx

@@ -1,6 +1,7 @@
 import { Metadata } from 'next';
 import { db } from '@/lib/db';
 import { auth } from '@/lib/auth';
+import { isBunnyUploadsFeatureEnabled } from '@/lib/feature-flags';
 import { redirect } from 'next/navigation';
 import { getCachedBunnyStorageStats, getCachedTotalStorage } from '@/lib/admin-stats';
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
@@ -173,7 +174,9 @@ export default async function AdminDashboardPage() {
                         <Film className="h-4 w-4 text-muted-foreground" />
                     </CardHeader>
                     <CardContent>
-                        <div className="text-2xl font-bold">{formatBytes(bunnyStorageStats.totalBytes)}</div>
+                        <div className="text-2xl font-bold">
+                            {isBunnyUploadsFeatureEnabled() ? formatBytes(bunnyStorageStats.totalBytes) : 'Disabled'}
+                        </div>
                     </CardContent>
                 </Card>
             </div>