feat(shipping): move delivery-time settings to Payload, polish product/cart CTAs

The delivery-time range (handling + transit days) was a hardcoded
HANDLING_DAYS/TRANSIT_DAYS_DE pair in lib/shipping.ts — changing it
needed a code deploy. Now sourced from Payload's new Shipping Settings
collection via getShippingSettings(), threaded down as a prop to the
few Client Components (Cart/Checkout/VersandModal) that can't fetch it
themselves, with the old code constants removed.

Also: the delivery-time note is now shown on every purchase CTA (shop
grid, home spotlight, ToDo-Karten hero + pricing panel), not just one
of them — required next to each buy button per Art. 246a §1 Abs.1
Nr.8 EGBGB, not just somewhere reachable via a link. Checkout's
sidebar was missing the "ab 39€ kostenlos" note Cart already had;
that's fixed too, and both now show the delivery-time range on its own
line instead of crammed onto the shipping-cost line.

Related smaller fixes bundled in since they touch the same files:
price/delivery-time spacing tightened into its own group, the
redundant "Sichere Zahlung" note under Cart's checkout button (already
shown via the trustBadges list right below) replaced with "Sichere
SSL-Verschlüsselung" to match Checkout, and ToDo-Karten's pricing panel
no longer shows a premature payment-security note at the add-to-cart
step.

app/checkout/page.tsx

@@ -2,7 +2,7 @@ import type { Metadata } from "next";
 import { CheckoutContent } from "./components/CheckoutContent";
 import { TrustRow } from "../components/TrustRow";
 import { Footer } from "../components/Footer";
-import { getShippingMethods, getPaymentMethods, getCartTrustBadges } from "../lib/payload";
+import { getShippingMethods, getPaymentMethods, getCartTrustBadges, getShippingSettings } from "../lib/payload";
 
 // robots: noindex — transactional page, same reasoning as /cart.
 export const metadata: Metadata = {
@@ -15,16 +15,22 @@ export const metadata: Metadata = {
 };
 
 export default async function CheckoutPage() {
-  const [shippingMethods, paymentMethods, trustBadges] = await Promise.all([
+  const [shippingMethods, paymentMethods, trustBadges, shippingSettings] = await Promise.all([
     getShippingMethods(),
     getPaymentMethods(),
     getCartTrustBadges(),
+    getShippingSettings(),
   ]);
 
   return (
     <>
       <main className="flex flex-col flex-1 bg-bg-base">
-        <CheckoutContent shippingMethods={shippingMethods} paymentMethods={paymentMethods} trustBadges={trustBadges} />
+        <CheckoutContent
+          shippingMethods={shippingMethods}
+          paymentMethods={paymentMethods}
+          trustBadges={trustBadges}
+          shippingSettings={shippingSettings}
+        />
         <TrustRow />
       </main>
       <Footer />