fix: read announcement id from live URL instead of serialized SSR data

The announcement id was extracted in the universal load function and serialized
into SSR HTML. When a CDN cached one announcement URL and served it for another,
the baked-in id caused the wrong announcement to render on direct page load.

Now selectedId derives from page.url (the actual browser URL) rather than
data.id, making the page immune to CDN cache cross-contamination.

Author: mostafaNazari702

src/routes/announcements/+page.svelte

@@ -19,7 +19,7 @@
 
 	let { data } = $props();
 
-	let selectedId = $derived(data.id);
+	let selectedId = $derived(page.url.searchParams.get('id'));
 
 	const initialParams = browser
 		? new URL(window.location.href).searchParams

src/routes/announcements/+page.ts

@@ -1,9 +1,7 @@
 import type { PageLoad } from './$types';
 
-export const load: PageLoad = ({ url, data }) => {
-	const id = url.searchParams.get('id');
+export const load: PageLoad = ({ data }) => {
 	return {
-		id,
 		announcements: data.announcements
 	};
 };