feat(chronik): rename route and heading to Aktivitäten

/chronik → /aktivitaeten; heading updated in all three locales.
Component folder (lib/components/chronik/) stays unchanged — internal
implementation detail, not user-facing.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/e2e/accessibility.spec.ts

@@ -10,7 +10,7 @@ import { test, expect } from '@playwright/test';
 const AUTHENTICATED_PAGES = [
 	{ name: 'home', path: '/' },
 	{ name: 'persons', path: '/persons' },
-	{ name: 'chronik', path: '/chronik' },
+	{ name: 'aktivitaeten', path: '/aktivitaeten' },
 	{ name: 'admin', path: '/admin' }
 ];