fix(vikon): use vikon_core redirect_uri for OAuth (registered on VIKON server)

- vikon_core/update/index.php now redirects OAuth callback to /dashboard/vikon-updates
- Vue frontend sends redirect_uri=https://www.ntspi.ru/vikon_core/update/index.php
- This URL is registered on db-nica.ru for client_id=542

public/vikon_core/update/index.php

@@ -0,0 +1,13 @@
+<?php
+$code = isset($_GET['code']) ? $_GET['code'] : '';
+$state = isset($_GET['state']) ? $_GET['state'] : '';
+
+$query = http_build_query(array_filter([
+    'code'  => $code,
+    'state' => $state,
+]));
+
+$redirectUrl = '/dashboard/vikon-updates' . ($query ? '?' . $query : '');
+
+header('Location: ' . $redirectUrl, true, 302);
+exit;