frontend: hide GetQuotas in sidebar until endpoint data loads

Add GetQuotas to the early-return false switch in isSupported() so it
doesn't flash in the sidebar during MFE init when endpointCompatibility
is still null.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: malinskibeniamin

frontend/src/state/supported-features.ts

@@ -91,6 +91,7 @@ export function isSupported(f: FeatureEntry): boolean {
       case Feature.SchemaRegistryACLApi.endpoint:
       case Feature.ShadowLinkService.endpoint:
       case Feature.TracingService.endpoint:
+      case Feature.GetQuotas.endpoint:
         return false;
       default:
         return true;