Initial SvelteKit frontend port of windwiderstand.de

Full parity with Astro site: content rows, post/tag routes, pagination,
event badges + OSM map, comments, Live-Search via /api/search-index,
CMS image proxy, RSS, sitemap.

Deploy: Dockerfile + docker-compose.prod.yml + Gitea Actions workflow
to build + push to git.pm86.de registry and ssh-deploy to Contabo.

src/lib/components/TranslationProvider.svelte

@@ -0,0 +1,25 @@
+<script lang="ts">
+  import { setContext } from "svelte";
+  import type { Snippet } from "svelte";
+  import type { Translations, TranslationReplacements } from "$lib/translations";
+  import { T_CONTEXT_KEY, replacePlaceholders } from "$lib/translations";
+
+  let {
+    translations = {},
+    children,
+  }: {
+    translations?: Translations;
+    children?: Snippet;
+  } = $props();
+
+  const t = (key: string, replacements?: TranslationReplacements): string => {
+    const raw = translations?.[key] ?? key;
+    return replacePlaceholders(raw, replacements);
+  };
+
+  setContext(T_CONTEXT_KEY, t);
+</script>
+
+{#if children}
+  {@render children()}
+{/if}