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/lib/shipping.ts

@@ -1,17 +1,14 @@
-// Single source of truth for shipping numbers/timeframes — consumed by
-// both the cart's order summary (CartContent.tsx) and the /versand policy
-// page, so the two can never drift apart.
+// Single source of truth for shipping numbers — consumed by both the
+// cart's order summary (CartContent.tsx) and the /versand policy page, so
+// the two can never drift apart.
+//
+// The delivery-timeframe numbers (handling/transit days, Art. 246a § 1
+// Abs. 1 Nr. 8 EGBGB) used to live here too, but now come from Payload's
+// Shipping Settings collection instead (see lib/payload.ts's
+// getShippingSettings()) — that duplication is exactly why the
+// ShippingMethods CMS title once carried a different, drifted day-range
+// than this file did. Cost/threshold below have the same drift risk
+// against Payload's ShippingMethods price/freeShippingThreshold fields,
+// not yet addressed here.
 export const SHIPPING_COST = 2.9;
 export const FREE_SHIPPING_THRESHOLD = 39;
-
-// Kept as an explicit range (not "so schnell wie möglich") per Art. 246a
-// § 1 Abs. 1 Nr. 8 EGBGB — German law requires disclosing a concrete
-// delivery timeframe before contract conclusion, and split into
-// Bearbeitungszeit/Versanddauer so it's clear whether processing time is
-// included in the stated number, not just a single ambiguous figure.
-export const HANDLING_DAYS = { min: 1, max: 2 };
-export const TRANSIT_DAYS_DE = { min: 2, max: 4 };
-export const TOTAL_DAYS_DE = {
-  min: HANDLING_DAYS.min + TRANSIT_DAYS_DE.min,
-  max: HANDLING_DAYS.max + TRANSIT_DAYS_DE.max,
-};