Separate system operations from core objects in GraphQL endpoints (#12977)

Moves system-level operations (auth, billing, admin) to use the
/metadata endpoint instead of /graphql.

This cleans up the endpoint separation so /graphql is purely for core
objects (Company, People, etc.) and /metadata handles all system
operations.

Part of prep work for webhook/API key core migration.

packages/twenty-front/src/modules/workflow/hooks/useComputeStepOutputSchema.ts

@@ -1,18 +1,19 @@
+import { useApolloCoreClient } from '@/object-metadata/hooks/useApolloCoreClient';
 import { COMPUTE_STEP_OUTPUT_SCHEMA } from '@/workflow/graphql/mutations/computeStepOutputSchema';
-import { useApolloClient, useMutation } from '@apollo/client';
+import { useMutation } from '@apollo/client';
 import {
   ComputeStepOutputSchemaInput,
   ComputeStepOutputSchemaMutation,
   ComputeStepOutputSchemaMutationVariables,
-} from '~/generated/graphql';
+} from '~/generated-metadata/graphql';
 
 export const useComputeStepOutputSchema = () => {
-  const apolloClient = useApolloClient();
+  const apolloCoreClient = useApolloCoreClient();
   const [mutate] = useMutation<
     ComputeStepOutputSchemaMutation,
     ComputeStepOutputSchemaMutationVariables
   >(COMPUTE_STEP_OUTPUT_SCHEMA, {
-    client: apolloClient,
+    client: apolloCoreClient,
   });
 
   const computeStepOutputSchema = async (