fix(login): redirect authenticated users away from login page

Authenticated users visiting /login are immediately redirected: admins to /today, all others to /.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

frontend/src/routes/login/+page.svelte

@@ -1,5 +1,6 @@
 <script lang="ts">
 	import { resolve } from '$app/paths';
+	import { goto } from '$app/navigation';
 	import { Button } from '$lib/components/ui/button/index.js';
 	import { Input } from '$lib/components/ui/input/index.js';
 	import { Label } from '$lib/components/ui/label/index.js';
@@ -7,6 +8,14 @@
 	import { Checkbox } from '$lib/components/ui/checkbox/index.js';
 	import RequiredLabel from '$lib/components/layout/RequiredLabel.svelte';
 	import { SvelteDate } from 'svelte/reactivity';
+	import { authStore } from '$lib/stores/auth.svelte.js';
+
+	// Redirect authenticated users away from login page
+	$effect(() => {
+		if (authStore.isAuthenticated && authStore.hasLoaded) {
+			goto(authStore.isAdmin() ? resolve('/today') : resolve('/'));
+		}
+	});
 
 	// zxcvbn-ts imports
 	import { zxcvbn, zxcvbnOptions } from '@zxcvbn-ts/core';