Use npm ci instead of npm install during build (#1080)

Currently the client build is not reproducible since, each time you run
`make build-client` the package lockfile is updated. This should be
handled separately by `make gen-package-lock` when developers actually
want to update the dependencies.

`npm ci` installs dependencies directly from the lockfile without
updating them, making builds reproducible.

client/Makefile

@@ -2,6 +2,10 @@
 clean:
 	rm -rf node_modules
 
+.PHONY: ci
+ci:
+	npm ci client
+
 .PHONY: install
 install:
 	npm install client