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/components/CheckoutContent.tsx

@@ -10,7 +10,7 @@ import { Reveal } from "../../components/Reveal";
 import { VersandModal } from "../../components/VersandModal";
 import { CheckoutSteps } from "../../components/CheckoutSteps";
 import { ORDER_KEY, generateOrderNumber, type OrderSnapshot } from "../../lib/order";
-import type { ShippingMethod, PaymentMethod, TrustBadge } from "../../lib/payload";
+import type { ShippingMethod, PaymentMethod, TrustBadge, ShippingSettings } from "../../lib/payload";
 
 function FormField({
   label,
@@ -32,10 +32,15 @@ export function CheckoutContent({
   shippingMethods,
   paymentMethods,
   trustBadges,
+  shippingSettings,
 }: {
   shippingMethods: ShippingMethod[];
   paymentMethods: PaymentMethod[];
   trustBadges: TrustBadge[];
+  /** Delivery-time disclosure (Payload's Shipping Settings) — named
+   * "shippingSettings", not "shipping", since that name is already the
+   * local computed shipping-cost value below. */
+  shippingSettings: ShippingSettings;
 }) {
   const cart = useCart();
   const products = useProducts();
@@ -386,7 +391,14 @@ export function CheckoutContent({
                   {shipping === 0 ? "Kostenlos" : formatPrice(shipping)}
                 </span>
               </div>
-              <p className="text-label text-text-muted">{selectedShipping?.description ?? "innerhalb Deutschlands"}</p>
+              <p className="text-label text-text-muted">
+                {shipping === 0 && selectedShipping?.freeShippingThreshold != null
+                  ? `ab ${formatPrice(selectedShipping.freeShippingThreshold)} innerhalb Deutschlands`
+                  : (selectedShipping?.description ?? "innerhalb Deutschlands")}
+              </p>
+              <p className="text-label text-text-muted">
+                Lieferzeit {shippingSettings.totalDays.min}–{shippingSettings.totalDays.max} Werktage
+              </p>
             </div>
 
             <div className="h-px bg-border w-full" />
@@ -448,7 +460,7 @@ export function CheckoutContent({
         </Reveal>
       </div>
 
-      <VersandModal open={versandOpen} onClose={() => setVersandOpen(false)} />
+      <VersandModal open={versandOpen} onClose={() => setVersandOpen(false)} shipping={shippingSettings} />
     </>
   );
 }