feat: Event-Bild im Social-Bild + UX-Verbesserungen

Social-Bild Calendar:
- Termin-Bild als Thumbnail neben QR-Code (Reihenfolge: QR | Bild)
- Wrapper transparent, Bild im natürlichen Aspect via object-fit:contain
  und fit=inside auf transform-API — kein Crop, kein Letterbox
- Wachstum auf qrSize+28 begrenzt
- Title-Fontsize bei vorhandenem Thumb zusätzlich verkleinert
- Eckige Kanten (kein border-radius) für QR-Box und Thumb

Calendar-Block:
- Vorschaubild im Termin-Item gleich gerendert: object-contain,
  max-w-24/max-h-24, kein Crop
- "Teilen"-Gruppe in Aktions-Toolbar bricht auf Mobile auf eigene
  Zeile um, Trennstrich nur auf sm+ sichtbar

Direkt-Link:
- Calendar: /kalender/?social=<slug> öffnet Modal automatisch
- Post: /post/<slug>?social=1 öffnet Modal automatisch
- Modal-Header: "Direktlink"-Button kopiert URL ins Clipboard

Skeleton-Loader:
- Animierter grauer Skeleton während Bild-Render via satori
- Per Theme-Wechsel resetten, fade-in via opacity-Transition
- Story-Container Fix: explizite 280x158 Maße statt aspect-ratio

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/components/SocialImageModal.svelte

@@ -21,6 +21,43 @@
   } = $props();
 
   let theme = $state<"wald" | "transparent-onlight" | "transparent-ondark">("wald");
+  let linkCopied = $state(false);
+
+  /** Direktlink, der dieses Modal erneut öffnet — abhängig von endpointBase. */
+  const directLink = $derived.by(() => {
+    if (typeof window === "undefined") return "";
+    const origin = window.location.origin;
+    if (endpointBase.includes("/calendar")) {
+      return `${origin}/kalender/?social=${encodeURIComponent(slug)}`;
+    }
+    if (endpointBase.includes("/post")) {
+      return `${origin}/post/${encodeURIComponent(slug)}?social=1`;
+    }
+    return `${origin}/`;
+  });
+
+  async function copyDirectLink() {
+    try {
+      await navigator.clipboard.writeText(directLink);
+      linkCopied = true;
+      setTimeout(() => (linkCopied = false), 2000);
+    } catch {
+      linkCopied = false;
+    }
+  }
+
+  // Loading-State pro Format. Skeleton wird angezeigt bis das jeweilige
+  // Bild fertig geladen ist. Bei Theme-Wechsel resetten.
+  let loadedOg = $state(false);
+  let loadedSq = $state(false);
+  let loadedStory = $state(false);
+  $effect(() => {
+    // Reset bei Theme-Änderung (neuer Request → neuer Loading-Zustand)
+    void theme;
+    loadedOg = false;
+    loadedSq = false;
+    loadedStory = false;
+  });
 
   const themeQ = $derived(theme === "wald" ? "" : `&theme=${theme}`);
   const ogUrl = $derived(`${endpointBase}/${slug}?format=og${themeQ}`);
@@ -55,14 +92,26 @@
           <p class="text-xs uppercase tracking-wider text-stein-500">Social-Bild</p>
           <p class="truncate text-sm font-semibold text-stein-800">{title}</p>
         </div>
-        <button
-          type="button"
-          onclick={onclose}
-          class="shrink-0 text-stein-400 hover:text-stein-700"
-          aria-label="Schließen"
-        >
-          <Icon icon="mdi:close" class="size-5" />
-        </button>
+        <div class="flex shrink-0 items-center gap-1">
+          <button
+            type="button"
+            onclick={copyDirectLink}
+            class="inline-flex items-center gap-1 rounded-md border border-stein-300 bg-white px-2 py-1 text-[11px] font-medium text-stein-700 hover:bg-stein-50"
+            title="Direktlink zu dieser Vorschau kopieren"
+            aria-label="Direktlink kopieren"
+          >
+            <Icon icon={linkCopied ? "mdi:check" : "mdi:link-variant"} class="size-3.5" />
+            {linkCopied ? "Kopiert" : "Direktlink"}
+          </button>
+          <button
+            type="button"
+            onclick={onclose}
+            class="text-stein-400 hover:text-stein-700"
+            aria-label="Schließen"
+          >
+            <Icon icon="mdi:close" class="size-5" />
+          </button>
+        </div>
       </div>
 
       <div class="mb-4 rounded-lg border border-stein-200 bg-stein-50 p-3">
@@ -108,7 +157,18 @@
       <div class="grid gap-4 sm:grid-cols-3">
         <div class="flex flex-col gap-2">
           <p class="text-xs font-medium text-stein-600">Quer · 1200 × 630</p>
-          <img src={ogUrl} alt="Social-Bild Quer" class="w-full rounded-sm border border-stein-200 {previewBg}" loading="eager" />
+          <div class="relative w-full aspect-[1200/630] rounded-sm border border-stein-200 overflow-hidden {previewBg}">
+            {#if !loadedOg}
+              <div class="absolute inset-0 animate-pulse bg-gradient-to-br from-stein-200 via-stein-300 to-stein-200"></div>
+            {/if}
+            <img
+              src={ogUrl}
+              alt="Social-Bild Quer"
+              class="absolute inset-0 h-full w-full transition-opacity duration-200 {loadedOg ? 'opacity-100' : 'opacity-0'}"
+              loading="eager"
+              onload={() => (loadedOg = true)}
+            />
+          </div>
           <a href={ogUrl} download={`${downloadPrefix}-${slug}-og-${theme}.png`} class="btn-outline btn-sm justify-center no-underline!">
             <Icon icon="mdi:download" class="size-3.5" />
             Quer herunterladen
@@ -116,7 +176,18 @@
         </div>
         <div class="flex flex-col gap-2">
           <p class="text-xs font-medium text-stein-600">Quadrat · 1080 × 1080</p>
-          <img src={sqUrl} alt="Social-Bild Quadrat" class="mx-auto w-full rounded-sm border border-stein-200 {previewBg}" loading="eager" />
+          <div class="relative mx-auto w-full aspect-square rounded-sm border border-stein-200 overflow-hidden {previewBg}">
+            {#if !loadedSq}
+              <div class="absolute inset-0 animate-pulse bg-gradient-to-br from-stein-200 via-stein-300 to-stein-200"></div>
+            {/if}
+            <img
+              src={sqUrl}
+              alt="Social-Bild Quadrat"
+              class="absolute inset-0 h-full w-full transition-opacity duration-200 {loadedSq ? 'opacity-100' : 'opacity-0'}"
+              loading="eager"
+              onload={() => (loadedSq = true)}
+            />
+          </div>
           <a href={sqUrl} download={`${downloadPrefix}-${slug}-square-${theme}.png`} class="btn-outline btn-sm justify-center no-underline!">
             <Icon icon="mdi:download" class="size-3.5" />
             Quadrat herunterladen
@@ -124,7 +195,18 @@
         </div>
         <div class="flex flex-col gap-2">
           <p class="text-xs font-medium text-stein-600">Story · 1080 × 1920</p>
-          <img src={storyUrl} alt="Social-Bild Story" class="mx-auto w-auto max-h-[280px] rounded-sm border border-stein-200 {previewBg}" loading="eager" />
+          <div class="relative mx-auto h-[280px] w-[158px] rounded-sm border border-stein-200 overflow-hidden {previewBg}">
+            {#if !loadedStory}
+              <div class="absolute inset-0 animate-pulse bg-gradient-to-br from-stein-200 via-stein-300 to-stein-200"></div>
+            {/if}
+            <img
+              src={storyUrl}
+              alt="Social-Bild Story"
+              class="absolute inset-0 h-full w-full transition-opacity duration-200 {loadedStory ? 'opacity-100' : 'opacity-0'}"
+              loading="eager"
+              onload={() => (loadedStory = true)}
+            />
+          </div>
           <a href={storyUrl} download={`${downloadPrefix}-${slug}-story-${theme}.png`} class="btn-outline btn-sm justify-center no-underline!">
             <Icon icon="mdi:download" class="size-3.5" />
             Story herunterladen