feat(layout): add global announcement banner above nav

Adds AnnouncementBanner component fed by a new top_banner CMS entry
(site-announcement). Extended top_banner schema and TS types with
optional link + linkLabel fields. Rendered inline-markdown text.

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

src/routes/+layout.server.ts

@@ -15,6 +15,7 @@ import type {
   NavigationEntry,
   FooterEntry,
   PageConfigEntry,
+  TopBannerEntry,
 } from '$lib/cms';
 import { ensureTransformedImage } from '$lib/rusty-image';
 import {
@@ -84,6 +85,7 @@ export const load: LayoutServerLoad = async ({ locals, route }) => {
   let bootstrapNavSocial: NavigationEntry | null = null;
   let bootstrapFooter: FooterEntry | null = null;
   let bootstrapConfig: PageConfigEntry | null = null;
+  let bootstrapTopBanner: TopBannerEntry | null = null;
   try {
     const batch = await batchFetch([
       {
@@ -114,11 +116,17 @@ export const load: LayoutServerLoad = async ({ locals, route }) => {
         locale: 'de',
         resolve: 'logo',
       },
+      {
+        id: 'topBanner',
+        collection: 'top_banner',
+        slug: 'site-announcement',
+      },
     ]);
     bootstrapNavHeader = batchData<NavigationEntry>(batch.results.navHeader);
     bootstrapNavSocial = batchData<NavigationEntry>(batch.results.navSocial);
     bootstrapFooter = batchData<FooterEntry>(batch.results.footer);
     bootstrapConfig = batchData<PageConfigEntry>(batch.results.config);
+    bootstrapTopBanner = batchData<TopBannerEntry>(batch.results.topBanner);
   } catch (err) {
     /* CMS nicht erreichbar — alle Felder bleiben null, Page rendert ohne. */
     logWarn('layout.bootstrap', err);
@@ -328,5 +336,6 @@ export const load: LayoutServerLoad = async ({ locals, route }) => {
     seoDescriptionTemplate: pageConfig?.seoDescription ?? null,
     analyticsPm86SiteId:
       (pageConfig as { analyticsPm86SiteId?: string } | null)?.analyticsPm86SiteId ?? null,
+    announcementBanner: bootstrapTopBanner,
   };
 };

src/routes/+layout.svelte

@@ -6,6 +6,7 @@
   import HeaderOverlay from '$lib/components/HeaderOverlay.svelte';
   import Footer from '$lib/components/Footer.svelte';
   import TopBanner from '$lib/components/TopBanner.svelte';
+  import AnnouncementBanner from '$lib/components/AnnouncementBanner.svelte';
   import TranslationProvider from '$lib/components/TranslationProvider.svelte';
   import Breadcrumbs from '$lib/ui/Breadcrumbs.svelte';
   import type { LayoutData } from './$types';
@@ -291,6 +292,9 @@
       class="sr-only focus:not-sr-only focus:fixed focus:top-2 focus:left-2 focus:z-[100] focus:bg-white focus:px-3 focus:py-2 focus:shadow focus:outline focus:outline-2 focus:outline-wald-600 focus:rounded-xs"
     >Zum Inhalt springen</a>
     <div class="flex min-h-screen flex-col text-stein-900">
+      {#if data.announcementBanner}
+        <AnnouncementBanner banner={data.announcementBanner} />
+      {/if}
       {#if pageData?.preview || pageData?.previewDraft}
         <div
           class="sticky top-0 z-[90] w-full bg-erde-500 text-black shadow-sm"