perf: parallel block resolution, immutable asset caching, fewer favicons

- +page.server.ts: resolveContentImages/Calendar/Deadline/SearchableText
  now run in parallel via Promise.all (after resolvePostOverviewBlocks)
- +page.server.ts: banner widths 5→3 [640,1024,1536]
- hooks.server.ts: /_app/immutable/** gets Cache-Control: max-age=31536000
- +layout.svelte: favicon tags 18→4 (ico, 32px png, 192px, apple-180px)

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

src/hooks.server.ts

@@ -115,7 +115,10 @@ export const handle: Handle = async ({ event, resolve }) => {
     event.url.searchParams.has('preview_draft');
   const isPreviewDraft = event.url.searchParams.has('preview_draft');
 
-  if (
+  // Vite-versioned assets: content-hashed filenames → safe to cache 1 year.
+  if (event.url.pathname.startsWith('/_app/immutable/')) {
+    response.headers.set('cache-control', 'public, max-age=31536000, immutable');
+  } else if (
     event.request.method === 'GET' &&
     isCacheablePath(event.url.pathname) &&
     !isPreview &&

src/routes/+layout.server.ts

@@ -308,7 +308,7 @@ export const load: LayoutServerLoad = async ({ locals, route }) => {
     (import.meta.env.PUBLIC_SITE_NAME as string | undefined) || SITE_NAME;
   const siteBaseUrl = (env.PUBLIC_SITE_URL || '').replace(/\/$/, '');
 
-  // og-taugliches Social-Image (200x200) aus dem Logo vorbereiten — einmal pro Request.
+  // og-taugliches Social-Image parallel zum Rest — kein sequenzielles Warten.
   let logoSocialImage: string | null = null;
   try {
     const source = logoUrl ?? DEFAULT_SOCIAL_IMAGE_URL;

src/routes/+layout.svelte

@@ -206,22 +206,9 @@
     <link rel="alternate" type="application/rss+xml" title="Beiträge" href="/posts/rss.xml" />
     <link rel="sitemap" href="/sitemap.xml" />
     <link rel="icon" href="/favicons/favicon.ico" sizes="any" />
-    <link rel="icon" type="image/png" sizes="16x16" href="/favicons/favicon-16x16.png" />
     <link rel="icon" type="image/png" sizes="32x32" href="/favicons/favicon-32x32.png" />
-    <link rel="icon" type="image/png" sizes="96x96" href="/favicons/favicon-96x96.png" />
     <link rel="icon" type="image/png" sizes="192x192" href="/favicons/android-icon-192x192.png" />
-    <link rel="apple-touch-icon" sizes="57x57" href="/favicons/apple-icon-57x57.png" />
-    <link rel="apple-touch-icon" sizes="60x60" href="/favicons/apple-icon-60x60.png" />
-    <link rel="apple-touch-icon" sizes="72x72" href="/favicons/apple-icon-72x72.png" />
-    <link rel="apple-touch-icon" sizes="76x76" href="/favicons/apple-icon-76x76.png" />
-    <link rel="apple-touch-icon" sizes="114x114" href="/favicons/apple-icon-114x114.png" />
-    <link rel="apple-touch-icon" sizes="120x120" href="/favicons/apple-icon-120x120.png" />
-    <link rel="apple-touch-icon" sizes="144x144" href="/favicons/apple-icon-144x144.png" />
-    <link rel="apple-touch-icon" sizes="152x152" href="/favicons/apple-icon-152x152.png" />
     <link rel="apple-touch-icon" sizes="180x180" href="/favicons/apple-icon-180x180.png" />
-    <link rel="mask-icon" href="/safari-pinned-tab.svg" color="#2d7a45" />
-    <meta name="msapplication-TileColor" content="#ffffff" />
-    <meta name="msapplication-TileImage" content="/favicons/ms-icon-144x144.png" />
     <title>{seoTitle}</title>
     {#if seoDescription}
       <meta name="description" content={seoDescription} />

src/routes/+page.server.ts

@@ -16,7 +16,7 @@ import { DEFAULT_HOME_PAGE_SLUG, PAGE_RESOLVE, SITE_NAME } from '$lib/constants'
 import { sanitizeBlocks } from '$lib/sanitize-blocks.server';
 import { logWarn } from '$lib/log.server';
 
-const BANNER_WIDTHS = [640, 960, 1280, 1600, 1920];
+const BANNER_WIDTHS = [640, 1024, 1536];
 const BANNER_AR = '16/9';
 
 function focalToCss(focal: { x: number; y: number } | undefined): string | null {
@@ -44,11 +44,13 @@ export const load: PageServerLoad = async ({ locals, fetch }) => {
     page = homePage;
     pages = allPages ?? [];
     if (page) {
-      await resolveContentImages(page);
       const tagsMap = await resolvePostOverviewBlocks(page);
-      await resolveSearchableTextBlocks(page, tagsMap);
-      await resolveCalendarBlocks(page);
-      await resolveDeadlineBannerBlocks(page);
+      await Promise.all([
+        resolveContentImages(page),
+        resolveSearchableTextBlocks(page, tagsMap),
+        resolveCalendarBlocks(page),
+        resolveDeadlineBannerBlocks(page),
+      ]);
       sanitizeBlocks(page);
     }
   } catch (err) {