Add product image gallery, harden Klaro border reset, remove attribution link

ProductGallery.tsx (main image + thumbnail strip) wired into
TodoKartenHero.tsx, only replacing the static hero photo once a
product actually has extra gallery photos — no visual change
otherwise. Backend field: Products.gallery (see payload repo).

Klaro's hard black border was still showing after the previous
color-only pass — the targeted border:none rule wasn't enough, so
this blanket-resets border/outline on every .klaro descendant and
re-adds only the shadow this theme actually wants. Also disables the
"Realisiert mit Klaro!" attribution link (BSD-3-Clause has no
on-page-attribution requirement, Klaro's own disablePoweredBy flag
covers this cleanly).

Updates the frontend README with the gallery + Klaro fixes.

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

app/components/KlaroConsentManager.tsx

@@ -38,9 +38,14 @@ import { loadTrackingCode } from "../lib/loadTrackingCode";
 function KlaroTheme() {
   return (
     <style>{`
-      .klaro, .klaro * { box-sizing: border-box; }
+      /* Blanket reset first — the previous pass only targeted
+         .cookie-notice/.cookie-modal directly and a hard black border
+         still showed up in production (screenshot-confirmed), so every
+         descendant gets border/outline stripped here regardless of which
+         specific Klaro rule was actually drawing it; the two rules below
+         re-add exactly the borders this theme actually wants. */
+      .klaro, .klaro * { box-sizing: border-box; border: 0 !important; outline: 0 !important; }
       .klaro .cookie-notice, .klaro .cookie-modal {
-        border: none !important;
         box-shadow: 0 20px 44px -14px rgba(26,26,24,0.22), 0 4px 14px rgba(26,26,24,0.07) !important;
         border-radius: 18px !important;
         font-family: var(--font-inter), -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif !important;