improvement for the backend api

app/(dashboard)/analytics/costs/page.tsx

@@ -59,12 +59,12 @@ export default function AnalyticsCostsPage() {
       const [reportData, channelsData] = await Promise.all([
         analyticsApi.costs({ period, target_channel_id: targetChannelId }),
         channels.length > 0
-          ? Promise.resolve({ data: channels })
-          : channelsApi.list({}),
+          ? Promise.resolve({ target_channels: channels })
+          : channelsApi.list(),
       ]);
       setReport(reportData);
       if (channels.length === 0) {
-        setChannels(channelsData.data);
+        setChannels(channelsData.target_channels);
       }
     } catch (err: any) {
       setError(err?.error?.message || "Ошибка загрузки аналитики");