Replace npm run relay with make relay everywhere

The make relay target merges split graphql files into a single
schema.graphql before running the Relay compiler. All CI workflows,
the generate target, and documentation now use make relay.

Signed-off-by: Émile Ré <emile@getprobo.com>

.github/workflows/release.yaml

@@ -24,7 +24,7 @@ jobs:
         with:
           go: "false"
       - run: "npm --workspace @probo/emails run build"
-      - run: "npm run relay"
+      - run: "make relay"
       - name: "Build console"
         run: |
           npm --workspace @probo/console run check