Revert: exclude chat-cli from final Docker image (server-only)

CLI is built during Docker build to verify compilation, but only chatd
is included in the final image. CLI distributed separately.

Dockerfile

@@ -11,6 +11,5 @@ RUN go build -o /chat-cli ./cmd/chat-cli/
 # Final stage
 FROM alpine:latest
 COPY --from=builder /chatd /usr/local/bin/chatd
-COPY --from=builder /chat-cli /usr/local/bin/chat-cli
 EXPOSE 8080
 CMD ["chatd"]