feat: add ODT export via odf-kit with filename derived from heading

src/lib/export/odt.ts

@@ -0,0 +1,35 @@
+import type { Editor } from '@tiptap/core';
+import { tiptapToOdt } from 'odf-kit';
+
+export async function exportToOdt(editor: Editor): Promise<void> {
+  const json = editor.getJSON();
+  const odt = await tiptapToOdt(json);
+
+  const blob = new Blob([odt], {
+    type: 'application/vnd.oasis.opendocument.text',
+  });
+
+  const url = URL.createObjectURL(blob);
+  const a = document.createElement('a');
+  a.href = url;
+  a.download = getFilename(editor);
+  a.click();
+  URL.revokeObjectURL(url);
+}
+
+function getFilename(editor: Editor): string {
+  // Try to derive filename from first heading
+  const json = editor.getJSON();
+  const heading = json.content?.find(
+    (node) => node.type === 'heading' && node.content?.length
+  );
+  if (heading?.content?.[0]?.text) {
+    const name = heading.content[0].text
+      .slice(0, 50)
+      .replace(/[^a-zA-Z0-9\s-]/g, '')
+      .trim()
+      .replace(/\s+/g, '-');
+    if (name) return `${name}.odt`;
+  }
+  return 'document.odt';
+}