fix: forward session token in admin SSR load functions

Admin list queries (users, videos, articles) were using getGraphQLClient
without auth credentials, causing silent 403s on server-side loads. Now
extract session_token cookie and pass it to getAuthClient so the backend
sees the admin session on SSR requests.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/frontend/src/routes/admin/users/+page.server.ts

@@ -1,12 +1,13 @@
 import { adminListUsers } from "$lib/services";
 
-export async function load({ fetch, url }) {
+export async function load({ fetch, url, cookies }) {
+  const token = cookies.get("session_token") || "";
   const role = url.searchParams.get("role") || undefined;
   const search = url.searchParams.get("search") || undefined;
   const offset = parseInt(url.searchParams.get("offset") || "0", 10);
   const limit = 50;
 
-  const result = await adminListUsers({ role, search, limit, offset }, fetch).catch(() => ({
+  const result = await adminListUsers({ role, search, limit, offset }, fetch, token).catch(() => ({
     items: [],
     total: 0,
   }));