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.

lib/stripe.ts

@@ -1,9 +1,14 @@
 import Stripe from 'stripe';
+import { hasStripeConfig, isStripeBillingEnabled } from '@/lib/feature-flags';
 
 let stripeClient: Stripe | null = null;
 
 export function isStripeConfigured() {
-  return Boolean(process.env.STRIPE_SECRET_KEY && process.env.STRIPE_PRICE_ID);
+  return isStripeBillingEnabled();
+}
+
+export function hasStripeRuntimeConfig() {
+  return hasStripeConfig();
 }
 
 export function getStripe() {