refactor(help): drop standalone /help route, use workbench app

The help workbench module (lib/modules/help/ListView.svelte) already
renders the same HelpPage component with identical props. The
standalone route was redundant.

- Delete routes/(app)/help/+page.svelte
- Update PillNavigation helpHref to /?app=help

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

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

@@ -979,7 +979,7 @@
 					spiralHref="/?app=spiral"
 					creditsHref="/credits"
 					themesHref="/?app=themes"
-					helpHref="/help"
+					helpHref="/?app=help"
 					allAppsHref="/apps"
 					{spotlightActions}
 					{contentSearcher}

apps/mana/apps/web/src/routes/(app)/help/+page.svelte

@@ -1,34 +0,0 @@
-<script lang="ts">
-	import { goto } from '$app/navigation';
-	import { locale } from 'svelte-i18n';
-	import { HelpPage, getHelpTranslations } from '@mana/help';
-	import { PageHeader } from '@mana/shared-ui';
-	import { getManaHelpContent } from '$lib/content/help/index.js';
-
-	const content = $derived(getManaHelpContent($locale ?? 'de'));
-	const translations = $derived(
-		getHelpTranslations($locale ?? 'de', {
-			subtitle:
-				$locale === 'de'
-					? 'Finde Antworten und lerne Mana kennen'
-					: 'Find answers and learn how to use Mana',
-		})
-	);
-</script>
-
-<svelte:head>
-	<title>{translations.title} | Mana</title>
-</svelte:head>
-
-<PageHeader title={translations.title} backHref="/" sticky />
-
-<HelpPage
-	{content}
-	appName="Mana"
-	appId="mana"
-	{translations}
-	showBackButton={false}
-	showGettingStarted={false}
-	showChangelog={false}
-	defaultSection="faq"
-/>