feat: enhance environment configuration and CORS handling

- Added `NEXT_PUBLIC_APP_URL` and `NEXT_PUBLIC_CONTACT_EMAIL` to environment variables for frontend configuration.
- Updated CORS logic to support domain-based restrictions with dynamic origin validation.
- Improved frontend image hostname resolution using environment-driven URLs.
- Standardized contact email usage across the application.

frontend/src/app/layout.tsx

@@ -32,7 +32,7 @@ export const metadata: Metadata = {
 	openGraph: {
 		type: "website",
 		locale: "fr_FR",
-		url: "https://memegoat.local",
+		url: "/",
 		siteName: "MemeGoat",
 		title: "MemeGoat | Partagez vos meilleurs mèmes",
 		description: "La plateforme ultime pour les mèmes. Rejoignez le troupeau !",