Restructures frontend to a feature-based folder layout

Groups auth, setup, invitation, profile, users, cms, availability and
system code (services/hooks, components, schemas, mocks, pages) under
src/features/<name> instead of splitting by technical layer (api/,
components/, lib/schemas/, mocks/, pages/). Renames the old
connection-oriented `api` layer to `services` per feature, and splits
the monolithic api/types.ts into per-feature types.ts files (with
ProblemDetails/ApiResult merged into lib/api-client.ts as shared
infra). Layout-agnostic code (ui primitives, app shell, i18n, test
utils, lib) stays at the top level.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/features/cms/services/useUpdateCmsInstanceStatus.ts

@@ -0,0 +1,20 @@
+import { useMutation, useQueryClient, type UseMutationOptions } from '@tanstack/react-query';
+import { api } from '@/lib/api-client';
+import type { UpdateCmsInstanceStatusRequest, UpdateStatusResult } from './types';
+
+type UpdateVariables = { id: string } & UpdateCmsInstanceStatusRequest;
+
+export function useUpdateCmsInstanceStatus(
+    options?: Pick<UseMutationOptions<UpdateStatusResult, Error, UpdateVariables>, 'onSuccess' | 'onError'>,
+) {
+    const queryClient = useQueryClient();
+    return useMutation<UpdateStatusResult, Error, UpdateVariables>({
+        mutationFn: ({ id, ...body }) =>
+            api.put<UpdateStatusResult>(`/api/v1/CmsInstances/${id}/status`, body),
+        onSuccess: (data, variables, ...rest) => {
+            queryClient.invalidateQueries({ queryKey: ['cmsInstances'] });
+            options?.onSuccess?.(data, variables, ...rest);
+        },
+        onError: options?.onError,
+    });
+}