fix: don't state newsletter opt-in as a given before consent is checked

Both /cart's and /checkout's newsletter hint boxes phrased regular
marketing emails as an already-decided outcome ("bekommst du...").
The actual consent checkbox (unchecked by default) only exists on
/checkout's address form, and even there the copy didn't make the
outcome conditional on it. Pre-supposing opt-in like this is unlawful
under UWG/DSGVO (see the ECJ's Planet49 ruling on pre-checked consent) —
reworded both to frame it as conditional/an option, not a promise.

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

app/checkout/components/CheckoutContent.tsx

@@ -375,8 +375,14 @@ export function CheckoutContent() {
           <div className="bg-bg-muted flex gap-5 items-start p-6 rounded-md w-full">
             <img alt="" src="/icon-envelope-hint.png" className="h-8 w-10 shrink-0 object-contain" />
             <div className="flex flex-col gap-2 items-start flex-1 min-w-0 text-text-primary">
+              {/* Conditional on the (unchecked-by-default) consent
+                  checkbox above, not stated as a given — a pre-ticked
+                  opt-in would be unlawful (UWG/DSGVO, see the ECJ's
+                  Planet49 ruling on pre-checked consent), and this copy
+                  shouldn't promise emails as if opting in were already
+                  decided either. */}
               <p className="text-body-sm leading-[1.45]">
-                Nach deiner Bestellung bekommst du regelmäßig Impulse &amp; Tipps per E-Mail.
+                Wenn du oben zustimmst, bekommst du nach deiner Bestellung regelmäßig Impulse &amp; Tipps per E-Mail.
               </p>
               <p className="text-body-sm leading-[1.45]">
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