fix: Add a build system for the backend

backend/Makefile

@@ -1,10 +1,16 @@
 node_modules:
 	npm install
 
-.PHONY: build
-build:
-	npm run-script build
+WEBPACK_BUILD := ./node_modules/.bin/webpack-cli --config webpack.config.js
+
+.PHONY: prod
+prod:
+	${WEBPACK_BUILD} --env.NODE_ENV=production
+
+.PHONY: dev
+dev:
+	${WEBPACK_BUILD} --env.NODE_ENV=development
 
 .PHONY: start
-start:
-	node dist/main.js
+start: dev
+	node dist/backend/src/main.js