feat: add configurable web interface host port

Add WEB_HTTP_PORT environment variable to configure
the host port for the web interface (port 8888).
Container still uses 8888 internally, but host port
can be customized via .env file.

docker-compose.yml

@@ -33,5 +33,5 @@ services:
       - "${SEARCH_HTTP_PORT:-8001}:8001"
       - "${TRADE_HTTP_PORT:-8002}:8002"
       - "${GETPRICE_HTTP_PORT:-8003}:8003"
-      - "8888:8888"
+      - "${WEB_HTTP_PORT:-8888}:8888"
     restart: unless-stopped