app/not-found.tsx — root not-found handles all unmatched routes
automatically (Next 16, no global-not-found flag needed for a single
root layout). Hero (Ups. / subheading / CTA) with a natively-drawn
sticky-note illustration (Lora "404" + Caveat handwritten line, no
image asset needed), 3 help links (Startseite/Blog/Werkzeuge), a
decorative search bar (no search backend exists yet to wire it to),
photo+quote testimonial band, TrustRow, Footer. Sets robots: noindex.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Marco