fix: use declarative Navigate instead of navigate() in render + fix useEffect deps

Subscriptions.tsx: navigate() in render → <Navigate> component (React safe).
Subscription.tsx: same fix for multi-tariff redirect.
AdminUserDetail.tsx: useRef guard for one-time auto-select instead of
activeSubscriptionId in dependency array (prevented manual selection).

src/pages/AdminUserDetail.tsx

@@ -336,6 +336,7 @@ export default function AdminUserDetail() {
   const [subDays, setSubDays] = useState<number | ''>(30);
   const [selectedTariffId, setSelectedTariffId] = useState<number | null>(null);
   const [activeSubscriptionId, setActiveSubscriptionId] = useState<number | null>(null);
+  const hasAutoSelectedSub = useRef(false);
   const [subscriptionDetailView, setSubscriptionDetailView] = useState(false);
 
   // Promo group
@@ -782,13 +783,14 @@ export default function AdminUserDetail() {
   const selectedSub =
     userSubscriptions.find((s) => s.id === activeSubscriptionId) ?? user?.subscription ?? null;
 
-  // Auto-select first subscription when user loads
+  // Auto-select first subscription when user loads (one-time init)
   useEffect(() => {
-    if (user && userSubscriptions.length > 0 && !activeSubscriptionId) {
+    if (user && userSubscriptions.length > 0 && !hasAutoSelectedSub.current) {
       const activeSub = userSubscriptions.find((s) => s.is_active) ?? userSubscriptions[0];
       setActiveSubscriptionId(activeSub.id);
+      hasAutoSelectedSub.current = true;
     }
-  }, [user, userSubscriptions, activeSubscriptionId]);
+  }, [user, userSubscriptions]);
 
   const currentTariff = tariffs.find((t) => t.id === selectedSub?.tariff_id) || null;
 

src/pages/Subscription.tsx

@@ -1,7 +1,7 @@
 import { useState, useEffect, useRef, useCallback, memo } from 'react';
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
 import { useTranslation } from 'react-i18next';
-import { useNavigate, useParams } from 'react-router';
+import { Navigate, useNavigate, useParams } from 'react-router';
 import { subscriptionApi } from '../api/subscription';
 import { WebBackButton } from '../components/WebBackButton';
 import { useDestructiveConfirm } from '../platform/hooks/useNativeDialog';
@@ -456,8 +456,7 @@ export default function Subscription() {
 
   // In multi-tariff mode without a specific subscription ID, redirect to list
   if (isMultiTariff && !subscriptionId && !isLoading) {
-    navigate('/subscriptions', { replace: true });
-    return null;
+    return <Navigate to="/subscriptions" replace />;
   }
 
   if (isLoading) {

src/pages/Subscriptions.tsx

@@ -1,5 +1,5 @@
 import { useQuery } from '@tanstack/react-query';
-import { useNavigate } from 'react-router';
+import { Navigate, useNavigate } from 'react-router';
 import { useTranslation } from 'react-i18next';
 import { subscriptionApi } from '../api/subscription';
 import { useTheme } from '../hooks/useTheme';
@@ -68,8 +68,7 @@ export default function Subscriptions() {
 
   // Single-tariff mode with one subscription: skip list, go directly to detail
   if (data && !isMultiTariff && subscriptions.length === 1) {
-    navigate(`/subscriptions/${subscriptions[0].id}`, { replace: true });
-    return null;
+    return <Navigate to={`/subscriptions/${subscriptions[0].id}`} replace />;
   }
 
   return (