fix: ListReminders JSON解析 — Gateway返{reminders:[...]}而非裸数组

backend/ai-core/internal/tools/gateway_client.go

@@ -94,11 +94,13 @@ func (c *GatewayClient) ListReminders(ctx context.Context, userID, status string
 		return nil, fmt.Errorf("gateway returned %d: %s", resp.StatusCode, string(bodyBytes))
 	}
 
-	var reminders []Reminder
-	if err := json.NewDecoder(resp.Body).Decode(&reminders); err != nil {
+	var result struct {
+		Reminders []Reminder 
+	}
+	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
 		return nil, fmt.Errorf("decode response: %w", err)
 	}
-	return reminders, nil
+	return result.Reminders, nil
 }
 
 // DeleteReminder calls DELETE /api/v1/internal/reminders/:id on the Gateway.