fix(auth): mark /hilfe/transkription as public for prerender

The route exports prerender = true and is listed in
svelte.config.js's prerender.entries. Until now the auth hook
redirected unauthenticated requests to /login, so the prerender
crawler hit a 302 and the build failed with "marked as prerenderable,
but were not prerendered".

Adding the path to PUBLIC_PATHS lets the crawler render the static
HTML; consistent with the route's intent as a public help page.

Surfaced by #497 (the production Docker build is the first place
npm run build runs in CI).

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

frontend/src/hooks.server.ts

@@ -5,7 +5,14 @@ import { env } from 'process';
 import { cookieName, cookieMaxAge } from '$lib/paraglide/runtime';
 import { detectLocale } from '$lib/shared/server/locale';
 
-const PUBLIC_PATHS = ['/login', '/logout', '/forgot-password', '/reset-password', '/register'];
+const PUBLIC_PATHS = [
+	'/login',
+	'/logout',
+	'/forgot-password',
+	'/reset-password',
+	'/register',
+	'/hilfe/transkription' // prerendered help page — must be reachable without an auth cookie
+];
 
 const handleLocaleDetection: Handle = ({ event, resolve }) => {
 	if (!event.cookies.get(cookieName)) {