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/billing/hooks/useGetWorkflowNodeExecutionUsage.ts

@@ -3,7 +3,7 @@ import {
   BillingProductKey,
   SubscriptionStatus,
   useGetMeteredProductsUsageQuery,
-} from '~/generated/graphql';
+} from '~/generated-metadata/graphql';
 
 export const useGetWorkflowNodeExecutionUsage = () => {
   const subscriptionStatus = useSubscriptionStatus();