fix(embed): skip site chrome on /widget routes via root layout

(embed)/+layout@.svelte only resets intermediate layouts — root
+layout.svelte still wrapped every widget page with Header, Footer,
TopBanner, Breadcrumbs, Skip-Link, OG/JSON-LD/Analytics.

Root layout now derives isEmbed from $page.route.id (matches /(embed))
and renders just {@render children()} in that branch. svelte:head is
gated too: embed mode emits only the favicon, leaving the page free to
set its own <title> and noindex meta.

+layout.server.ts short-circuits the bootstrap batch (navigation,
footer, page_config, logo) for embed routes — saves one CMS roundtrip
+ logo transform per widget request, and avoids double-counting in
Umami/pm86 analytics when the widget is iframed elsewhere.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/routes/+layout.server.ts

@@ -48,9 +48,33 @@ function getSlugFromEntry(entry: NavLinkEntry): string {
   return e.slug ?? e._slug ?? '';
 }
 
-export const load: LayoutServerLoad = async ({ locals }) => {
+export const load: LayoutServerLoad = async ({ locals, route }) => {
   const translations = locals.translations ?? {};
 
+  // Embed-Routen ((embed)/...) brauchen kein Site-Chrome. Bootstrap-Batch
+  // wird übersprungen — spart 1 CMS-Roundtrip + Logo-Transform pro Request.
+  // Layout-Komponente rendert über `isEmbed` ohne Header/Footer/Banner.
+  if ((route.id ?? '').startsWith('/(embed)')) {
+    const siteName =
+      (import.meta.env.PUBLIC_SITE_NAME as string | undefined) || SITE_NAME;
+    const siteBaseUrl = (env.PUBLIC_SITE_URL || '').replace(/\/$/, '');
+    return {
+      headerLinks: [] as NavLink[],
+      socialLinks: [] as SocialLink[],
+      footerData: null as FooterEntry | null,
+      logoUrl: null as string | null,
+      logoSvgHtml: null as string | null,
+      logoSocialImage: null as string | null,
+      siteName,
+      siteBaseUrl,
+      translations,
+      pageConfig: null as PageConfigEntry | null,
+      seoTitleTemplate: null,
+      seoDescriptionTemplate: null,
+      analyticsPm86SiteId: null,
+    };
+  }
+
   // Layout-Bootstrap: Navigation (header + social), Footer, page_config in
   // einem einzigen HTTP-Roundtrip (POST /api/content/_batch). Reduziert von
   // 4 sequentiellen Calls auf 1. Page-/Post-Stubs gehen separat (sparse