feat: add FilesBlock interface and component integration

- Introduced FilesBlockItem and FilesBlockData interfaces to support file handling in the CMS.
- Integrated FilesBlock component into ContentRows.svelte for rendering file blocks.
- Updated block type handling to include support for files, enhancing content versatility.

src/lib/rusty-file.ts

@@ -0,0 +1,97 @@
+/**
+ * Datei-URLs für SvelteKit: /cms-files mit persistentem Server-Disk-Cache.
+ * Analog zu rusty-image.ts, aber für generische Dateien (PDF, DOCX, ...).
+ */
+
+export interface CmsFileField {
+  url: string;
+  title?: string;
+  description?: string;
+  size?: number;
+  mime?: string;
+  filename?: string;
+}
+
+/**
+ * Extrahiert URL/Title/Description aus einem CMS-File-Field
+ * (string oder { src, title?, description?, mime?, size?, ... }).
+ */
+export function extractCmsFileField(field: unknown): CmsFileField | null {
+  if (typeof field === 'string') {
+    const s = field.trim();
+    if (!s) return null;
+    return { url: s.startsWith('//') ? `https:${s}` : s };
+  }
+  if (field && typeof field === 'object') {
+    const o = field as {
+      src?: string;
+      file?: { url?: string };
+      title?: string;
+      description?: string;
+      size?: number;
+      mime?: string;
+      filename?: string;
+    };
+    const rawUrl =
+      typeof o.src === 'string' && o.src.trim()
+        ? o.src
+        : typeof o.file?.url === 'string' && o.file.url.trim()
+          ? o.file.url
+          : undefined;
+    if (!rawUrl) return null;
+    const url = rawUrl.startsWith('//') ? `https:${rawUrl}` : rawUrl;
+    return {
+      url,
+      ...(o.title ? { title: o.title } : {}),
+      ...(o.description ? { description: o.description } : {}),
+      ...(typeof o.size === 'number' ? { size: o.size } : {}),
+      ...(o.mime ? { mime: o.mime } : {}),
+      ...(o.filename ? { filename: o.filename } : {}),
+    };
+  }
+  return null;
+}
+
+export interface CmsFileUrlOptions {
+  /** Filename hint for Content-Disposition header. */
+  filename?: string;
+  /** Force download (Content-Disposition: attachment). */
+  download?: boolean;
+}
+
+/**
+ * Lokale Datei-URL: /cms-files?src=…&name=…&dl=…
+ * `src` = volle Datei-URL oder CMS-Asset-Pfad (`/api/assets/...`).
+ */
+export function getCmsFileUrl(src: string, opts: CmsFileUrlOptions = {}): string {
+  const params = new URLSearchParams();
+  params.set('src', src);
+  if (opts.filename) params.set('name', opts.filename);
+  if (opts.download) params.set('dl', '1');
+  return `/cms-files?${params.toString()}`;
+}
+
+const SIZE_UNITS = ['B', 'KB', 'MB', 'GB'];
+
+export function formatFileSize(bytes?: number): string | null {
+  if (typeof bytes !== 'number' || !Number.isFinite(bytes) || bytes <= 0) return null;
+  let b = bytes;
+  let i = 0;
+  while (b >= 1024 && i < SIZE_UNITS.length - 1) {
+    b /= 1024;
+    i++;
+  }
+  const rounded = b >= 10 || i === 0 ? Math.round(b) : Math.round(b * 10) / 10;
+  return `${rounded} ${SIZE_UNITS[i]}`;
+}
+
+export function fileExtFromUrl(url: string): string | null {
+  try {
+    const path = url.split('?')[0].split('#')[0];
+    const last = path.split('/').pop() ?? '';
+    const dot = last.lastIndexOf('.');
+    return dot >= 0 ? last.slice(dot + 1).toLowerCase() : null;
+  } catch {
+    return null;
+  }
+}