fix: hide Familienarchiv wordmark below sm breakpoint to save header space

On mobile the text consumed most of the header width, leaving no room
for the hamburger, theme toggle, and user menu. Uses hidden sm:inline —
aria-label on the anchor preserves screen reader access at all sizes.

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

frontend/src/routes/AppNav.svelte

@@ -30,7 +30,7 @@ function handleOverlayKeydown(event: KeyboardEvent) {
 <div class="flex items-center">
 	<div class="mr-10 flex flex-shrink-0 items-center">
 		<a href="/" class="flex items-center" aria-label="Familienarchiv">
-			<span class="font-sans text-xl font-bold tracking-widest text-ink uppercase"
+			<span class="hidden font-sans text-xl font-bold tracking-widest text-ink uppercase sm:inline"
 				>Familienarchiv</span
 			>
 		</a>