feat(admin-ui): Phase B frontend — notifications preferences route + UI

ordinis-admin-ui/src/api/mutations.ts

@@ -12,6 +12,7 @@ import {
   type DecisionRequest,
   type DictionaryDetail,
   type DraftResponse,
+  type NotificationPreferences,
   type PublishSchemaDraftRequest,
   type PublishSchemaDraftResult,
   type RecordResponse,
@@ -700,3 +701,43 @@ export const useMarkAllNotificationsRead = () => {
     },
   })
 }
+
+/**
+ * Phase B — update per-channel notification preferences. PUT upserts all 3
+ * каналов атомарно (backend @Transactional). Optimistic update — UI flips
+ * toggle instantly, onError refetch restores original state.
+ *
+ * <p>Cache key 'notifications/me/preferences' — separate from feed query
+ * (которая использует 'notifications/me'). Invalidate prefs alone не
+ * triggers feed refetch.
+ */
+export const useUpdateNotificationPreferences = () => {
+  const qc = useQueryClient()
+  return useMutation({
+    mutationFn: async (prefs: NotificationPreferences): Promise<NotificationPreferences> => {
+      const { data } = await apiClient.put<NotificationPreferences>(
+        '/me/notifications/preferences',
+        prefs,
+      )
+      return data
+    },
+    onMutate: async (next) => {
+      await qc.cancelQueries({ queryKey: ['notifications', 'me', 'preferences'] })
+      const prev = qc.getQueryData<NotificationPreferences>([
+        'notifications',
+        'me',
+        'preferences',
+      ])
+      qc.setQueryData(['notifications', 'me', 'preferences'], next)
+      return { prev }
+    },
+    onError: (_err, _next, ctx) => {
+      if (ctx?.prev) {
+        qc.setQueryData(['notifications', 'me', 'preferences'], ctx.prev)
+      }
+    },
+    onSettled: () => {
+      qc.invalidateQueries({ queryKey: ['notifications', 'me', 'preferences'] })
+    },
+  })
+}