fix(app-shell): instabile Zustands-Selektoren veroursachten haengende Lazy-Routen ("Dashboard loads forever") — Root Cause: moduleMenuOrder()/visibleModuleKeys() erzeugten bei jedem getSnapshot neue Map/Set-Objekte

frontend/src/hooks/useWorkspace.ts

@@ -1,4 +1,4 @@
-import { useEffect, useCallback } from 'react';
+import { useEffect, useCallback, useMemo } from 'react';
 import { useMyWorkspaces, useWorkspaceContext } from '@/api/hooks/workspaces';
 import { useWorkspaceStore, type WorkspaceInfo, type WorkspaceContextState } from '@/store/workspaceStore';
 import { useAuthStore } from '@/store/authStore';
@@ -62,7 +62,13 @@ export function useWorkspace() {
     return isModuleVisibleFromStore(moduleKey, isSystemAdmin);
   }, [isModuleVisibleFromStore, isSystemAdmin]);
 
-  const visibleModuleKeys = useWorkspaceStore(s => s.visibleModuleKeys());
+  // NOTE: derive from the stable `context` reference via useMemo —
+  // `s.visibleModuleKeys()` would create a NEW Set on every getSnapshot
+  // call, destabilizing useSyncExternalStore (same root cause as the
+  // Sidebar moduleMenuOrder infinite re-render loop).
+  const visibleModuleKeys = useMemo(() => new Set(
+    (context?.modules ?? []).filter(m => m.is_visible !== false).map(m => m.module_key),
+  ), [context]);
 
   return {
     activeWorkspaceId,