site: owner-only dashboard link in header, mobile menu and homepage (g then d from any page); /start skips the site chrome JS

- Header/footer moved to #lib/components/SiteChrome.svelte, returned by a universal
  +layout.ts load only for non-immersive pages, so /start and the book reader never
  download icon libraries, dropdowns or the bits-ui Sheet. /start: 36 -> 18 JS files,
  133 -> 78 KB gzip.
- Header logo is a hashed asset (inlined), so it is cached with the build.
- inlineStyleThreshold 4096: tiny page/component CSS is inlined into the HTML.
- Umami is not loaded on /start.

src/routes/+page.svelte

@@ -9,6 +9,7 @@
 	import Mail from 'lucide-svelte/icons/mail';
 	import BriefcaseBusiness from 'lucide-svelte/icons/briefcase-business';
 	import GraduationCap from 'lucide-svelte/icons/graduation-cap';
+	import LayoutDashboard from 'lucide-svelte/icons/layout-dashboard';
 	import type { PageProps } from './$types';
 
 	let { data }: PageProps = $props();
@@ -49,6 +50,22 @@
 </svelte:head>
 
 <div class="mx-auto max-w-6xl px-4 sm:px-6">
+	{#if data.isOwner}
+		<!-- Owner only: a shortcut to the private /start dashboard. Visitors never see it. -->
+		<a
+			href={resolve('/start')}
+			class="mt-4 flex items-center gap-3 rounded-md border border-[var(--site-border)] bg-[var(--site-surface)] px-4 py-3 hover:border-[var(--site-text)]"
+		>
+			<LayoutDashboard size={20} aria-hidden="true" />
+			<span class="min-w-0"
+				><span class="block font-medium">dashboard</span><span
+					class="block truncate text-sm text-[var(--site-muted)]"
+					>tasks, server, backups, notifications and links · g then d from any page</span
+				></span
+			>
+			<ArrowRight size={18} class="ml-auto shrink-0" aria-hidden="true" />
+		</a>
+	{/if}
 	<section
 		class="grid items-center gap-8 pt-7 pb-12 sm:py-20 md:grid-cols-[minmax(0,1fr)_minmax(0,320px)] md:gap-16"
 	>