Cap Newsletter card at 1280px, show an explicit "Keine Versandkosten" hint, generalize the /versand exemption note

- Newsletter.tsx: max-w-[1280px] mx-auto, matching /lebensuhr's own
  newsletter-style section and Footer.tsx's existing 1280px convention —
  previously unbounded and stretched edge-to-edge on wide viewports.
- Product pages: noShippingCost now shows "Keine Versandkosten" instead
  of just omitting "zzgl. Versand" silently.
- /versand's exemption note no longer implies only digital products can
  be exempt — noShippingCost is a general per-product flag.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/components/Newsletter.tsx

@@ -43,8 +43,15 @@ export function Newsletter({
       {/* Outer section padding — same fluid horizontal padding as all other sections */}
       <div className="px-[var(--layout-padding-x)] w-full">
 
+        {/* max-w-[1280px] mx-auto — the consistent default width for this
+            card, matching /lebensuhr's own newsletter-style "Bottom CTA"
+            section (same 1280px cap Footer.tsx already uses) and every
+            other narrow-viewport-friendly section on the site. Previously
+            unbounded here, so on wide desktop viewports this card stretched
+            edge-to-edge while /lebensuhr's version stayed centered and
+            noticeably narrower — reported 2026-07-29. */}
         {/* Rounded card: cream bg, stacks below sm (moved down from the old md:) */}
-        <Reveal className="bg-bg-muted flex flex-col sm:flex-row gap-8 sm:gap-12 items-center px-8 py-8 sm:py-0 rounded-md w-full">
+        <Reveal className="bg-bg-muted flex flex-col sm:flex-row gap-8 sm:gap-12 items-center px-8 py-8 sm:py-0 rounded-md w-full max-w-[1280px] mx-auto">
 
           {/* Left: copy — fixed width from sm+ so the form always gets the remaining space.
               Icon+text stacked (icon on top, centered) below sm: — side by