[CPL-20711] add a build arg for transport

Author: oshchyhol

docker/Dockerfile

@@ -1,11 +1,13 @@
 FROM node:22.15.1-slim AS base
 
 ARG APP_VERSION=development
+ARG TRANSPORT=stdio
 
 ENV NODE_ENV=production
 ENV COUPLER_API_HOST=https://app.coupler.io/mcp
 ENV LOG_LEVEL=silent
 ENV APP_VERSION=$APP_VERSION
+ENV TRANSPORT=$TRANSPORT
 
 WORKDIR /app