docs: fix repl login (#10295)

* fix < and > rendering in search results

* should fix auth window issues

* more fixes

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>

Author: xyzqm

sites/svelte.dev/src/routes/(authed)/+layout.svelte

@@ -11,6 +11,7 @@
 			);
 
 			window.addEventListener('message', function handler(event) {
+				if (event.data.source !== 'svelte-auth') return;
 				login_window.close();
 				window.removeEventListener('message', handler);
 				invalidateAll();

sites/svelte.dev/src/routes/auth/callback/+server.js

@@ -33,13 +33,13 @@ export async function GET({ url }) {
 			github_login: profile.login,
 			github_avatar_url: profile.avatar_url
 		};
-
 		const { sessionid, expires } = await session.create(user);
 
 		return new Response(
 			`
 			<script>
 				window.opener.postMessage({
+					source: 'svelte-auth',
 					user: ${uneval(user)}
 				}, window.location.origin);
 			</script>

sites/svelte.dev/src/routes/auth/login/+server.js

@@ -12,7 +12,7 @@ export const GET = client_id
 				}).toString();
 
 			redirect(302, Location);
-	  }
+		}
 	: () =>
 			new Response(
 				`