chore: add image build in makefile

Author: Peefy

Makefile

@@ -12,3 +12,7 @@ test:
 api:
 	curl http://localhost:2023/-/play/compile -X POST --data '{"body":"a=5 + 5"}' -H "content-type:application/json"
 	curl http://localhost:2023/-/play/fmt?body="a=1" -X POST -H "content-type:application/json"
+
+image:
+	docker build . -t kcllang/kcl-playground
+	docker push kcllang/kcl-playground