feat(design): designauswahl mit klemmbaustein-look als standard

Sechs Designs (Klemmbaustein, Warm, Nachtblau, Bonbon, Bauklotz,
Schlicht) als Tokens je data-design, gewaehlt unter Konto und pro Geraet
im Cookie gespeichert. Dazu Noppen, Steinkontur, Platzhalter fuer Sets
ohne Bild, neues Logo, lokal gebuendelte Schriften und eine Startseite
mit Steinreihe und naechstem Termin.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/(app)/sammlung/page.tsx

@@ -1,12 +1,14 @@
 import type { Metadata } from 'next';
 import Link from 'next/link';
-import { Boxes, Euro, ImageOff, Layers, PackageSearch } from 'lucide-react';
+import { Boxes, Euro, Layers, PackageSearch } from 'lucide-react';
+import { SetPlaceholder } from '@/components/brick/set-placeholder';
+import { Studs } from '@/components/brick/studs';
 import { CollectorFilter } from '@/components/layout/collector-filter';
 import { CollectionFilters } from '@/components/sammlung/collection-filters';
 import { Badge } from '@/components/ui/badge';
 import { Card, CardContent } from '@/components/ui/card';
 import { formatDate, formatNumber, pluralize } from '@/lib/format';
-import { collectorBadgeClass } from '@/lib/collector-colors';
+import { collectorBadgeClass, collectorDotClass } from '@/lib/collector-colors';
 import { setImageSrc } from '@/lib/images';
 import { completenessLabel, statusLabel } from '@/lib/labels';
 import { formatEuro } from '@/lib/money';
@@ -122,23 +124,31 @@ export default async function SammlungPage({ searchParams }: { searchParams: Sea
           </Link>
         </div>
       ) : (
-        <ul className="divide-y divide-border rounded-lg border border-border">
+        <ul className="space-y-5 pt-2">
           {items.map((item) => {
             const image = setImageSrc(item);
             return (
-              <li key={item.id}>
+              <li key={item.id} className="relative">
+                {/* The studs carry the collector's colour once there is more than one. */}
+                <Studs
+                  studClassName={
+                    collectors.length > 1 ? collectorDotClass(item.collectorColor) : undefined
+                  }
+                />
                 <Link
                   href={`/katalog/${item.setId}`}
-                  className="flex items-center gap-3 p-3 transition-colors hover:bg-muted/50"
+                  className="brick flex items-center gap-3 rounded-xl bg-card p-3 transition-colors hover:bg-muted/50"
                 >
-                  <div className="size-14 shrink-0 overflow-hidden rounded-lg border border-border bg-muted">
+                  <div className="size-16 shrink-0 overflow-hidden rounded-lg border-[length:max(1px,var(--edge-w))] border-edge bg-muted">
                     {image ? (
                       // eslint-disable-next-line @next/next/no-img-element
                       <img src={image} alt="" loading="lazy" className="size-full object-contain" />
                     ) : (
-                      <div className="flex size-full items-center justify-center text-muted-foreground">
-                        <ImageOff className="size-5" aria-hidden />
-                      </div>
+                      <SetPlaceholder
+                        setNumber={item.setNumber}
+                        manufacturerName={item.manufacturerName}
+                        size="sm"
+                      />
                     )}
                   </div>