feat(post-overview): add "Alle Beiträge" link with arrow

Adds i18n-keyed link under the PostOverview block linking to /posts/.
New key post_overview_all wired through translations prop from
ContentRows → PostOverviewBlock.

src/components/blocks/PostOverviewBlock.svelte

@@ -5,8 +5,20 @@
   import type { PostOverviewBlockData } from "../../lib/block-types";
   import type { PostEntry } from "../../lib/cms";
   import { postHref } from "../../lib/blog-utils";
+  import { t as tStatic, T } from "../../lib/translations";
+  import type { Translations } from "../../lib/translations";
 
-  let { block, class: className = "" }: { block: PostOverviewBlockData; class?: string } = $props();
+  let {
+    block,
+    class: className = "",
+    translations = {},
+  }: {
+    block: PostOverviewBlockData;
+    class?: string;
+    translations?: Translations | null;
+  } = $props();
+
+  const t = (key: Parameters<typeof tStatic>[1]) => tStatic(translations ?? null, key);
 
   marked.setOptions({ gfm: true });
   const textHtml = $derived(
@@ -45,4 +57,13 @@
       {/each}
     </div>
   {/if}
+
+  {#if posts.length > 0}
+    <div class="mt-3 text-sm">
+      <a href="/posts/" class="inline-flex items-center gap-1 text-zinc-700 hover:text-zinc-900 hover:underline">
+        {t(T.post_overview_all)}
+        <span aria-hidden="true">→</span>
+      </a>
+    </div>
+  {/if}
 </div>