refactor: resolve() internal links instead of plain hrefs

Type-checks every link against the real route tree. Caught a dead one: the
book page linked tags to /tag/{id}, a route that has never existed.

frontend/src/routes/(root)/settings/account/+page.svelte

@@ -1,4 +1,5 @@
 <script lang="ts">
+	import { resolve } from '$app/paths';
 	import { goto } from '$app/navigation';
 	import { logout } from '$lib/api';
 	import { Button } from '$lib/components/ui/button/index.js';
@@ -12,7 +13,7 @@
 	<Button
 		onclick={async () => {
 			await logout();
-			goto('/login');
+			goto(resolve('/login'));
 		}}
 		variant="outline"
 		class="w-32"