feat(manacore/web): wire reminder scheduler into app layout

Start createReminderScheduler with todoReminderSource on auth ready.
Request notification permission on app mount. Stop scheduler on destroy.
Todo reminders now fire browser notifications when dueDate - minutesBefore
is reached.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/manacore/apps/web/src/routes/(app)/+layout.svelte

@@ -3,6 +3,8 @@
 	import { page } from '$app/stores';
 	import type { Snippet } from 'svelte';
 	import { onDestroy, setContext } from 'svelte';
+	import { createReminderScheduler, notificationService } from '@manacore/shared-stores';
+	import { todoReminderSource } from '$lib/modules/todo/reminder-source';
 	import KeyboardShortcutsModal from '$lib/components/KeyboardShortcutsModal.svelte';
 	import SessionWarning from '$lib/components/SessionWarning.svelte';
 	import { locale, _ } from 'svelte-i18n';
@@ -207,6 +209,9 @@
 		import.meta.env.PUBLIC_SYNC_SERVER_URL ||
 		'http://localhost:3050';
 	let unifiedSync: ReturnType<typeof createUnifiedSync> | null = null;
+	const reminderScheduler = createReminderScheduler({
+		sources: [todoReminderSource],
+	});
 
 	async function handleSignOut() {
 		unifiedSync?.stopAll();
@@ -271,6 +276,10 @@
 			}
 		}
 
+		// Phase B2: Start reminder scheduler
+		reminderScheduler.start();
+		notificationService.requestPermission();
+
 		// Phase C: Guest mode — welcome modal + nudge
 		if (!authStore.isAuthenticated) {
 			markAsGuest();
@@ -283,6 +292,7 @@
 
 	onDestroy(() => {
 		unifiedSync?.stopAll();
+		reminderScheduler.stop();
 		guestMode?.destroy();
 	});