Update application and database port configurations

Adjusted Docker configuration, exposing PostgreSQL on port 4523 and the application on internal port 5555, with Nginx proxying requests to the application. Updated Dockerfile, docker-compose.yml, and DOCKER.md accordingly.

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Replit-Commit-Session-Id: ae4037a0-2a6f-4530-9bac-79b543286bda
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.env.example

@@ -9,9 +9,9 @@ PGHOST=postgres
 DATABASE_URL=postgresql://socialflow:changeme@postgres:5432/socialflow
 
 # Configuration de l'application
-PORT=4523
+PORT=5555
 NODE_ENV=production
-APP_URL=http://localhost:4523
+APP_URL=http://localhost:5555
 
 # Clé secrète pour les sessions (CHANGEZ CETTE VALEUR)
 SESSION_SECRET=your-secret-key-change-me-to-random-string