infra: change host port from 3000 to 3847

Port 3000 is already in use on the server.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker-compose.prod.yml

@@ -18,7 +18,7 @@ services:
     image: code.letsbe.solutions/letsbe/letsbebiz-site:latest
     restart: unless-stopped
     ports:
-      - "127.0.0.1:3000:3000"
+      - "127.0.0.1:3847:3000"
     environment:
       DATABASE_URI: postgresql://${POSTGRES_USER:-letsbe}:${POSTGRES_PASSWORD}@db:5432/letsbe
       PAYLOAD_SECRET: ${PAYLOAD_SECRET}