Update NEXTAUTH_URL in docker-compose.yml to support environment variable fallback, enhancing configuration flexibility.

docker-compose.yml

@@ -11,7 +11,7 @@ services:
     environment:
       - NODE_ENV=production
       - DATABASE_URL=file:/app/data/dev.db
-      - NEXTAUTH_URL=http://localhost:3000
+      - NEXTAUTH_URL=${NEXTAUTH_URL:-http://localhost:3000}
       - NEXTAUTH_SECRET=${NEXTAUTH_SECRET:-change-this-secret-in-production}
     volumes:
       # Persist database (override DATA_PATH env var to change location)