fix: handle undefined publishDate to prevent Invalid time value crash

packages/cli/src/lib/atproto.ts

···
 	config: PublisherConfig,
 	coverImage?: BlobObject,
 ): Promise<string> {
-	const publishDate = new Date(post.frontmatter.publishDate);
+	const _d = new Date(post.frontmatter.publishDate ?? "");
+	const publishDate = isNaN(_d.getTime()) ? new Date() : _d;
 	const trimmedContent = post.content.trim();
 	const textContent = getTextContent(post, config.textContentField);
 	const titleMatch = trimmedContent.match(/^# (.+)$/m);
···
 		.pop()!
 		.replace(/\.pub$/, "");
 	const finalPath = `/pub/${rkey}/${slugName}`;
-	const publishDate = new Date(post.frontmatter.publishDate);
+	const _d = new Date(post.frontmatter.publishDate ?? "");
+	const publishDate = isNaN(_d.getTime()) ? new Date() : _d;
 	const trimmedContent = post.content.trim();
 	const textContent = getTextContent(post, config.textContentField);
 	const titleMatch = trimmedContent.match(/^# (.+)$/m);

packages/remanso-cli/src/lib/note.ts

···
 import { detectLanguage } from "./detect-languages";
 
 const LEXICON = "space.remanso.note";
+
+function toISODate(value: string | undefined): string {
+	const d = new Date(value ?? "");
+	return isNaN(d.getTime()) ? new Date().toISOString() : d.toISOString();
+}
 const MAX_CONTENT = 30000;
 const MIN_CONTENT_FOR_TRANSLATION = 400;
 
···
 	post: BlogPost,
 	options: NoteOptions,
 ): Promise<Record<string, unknown>> {
-	const publishDate = new Date(post.frontmatter.publishDate).toISOString();
+	const publishDate = toISODate(post.frontmatter.publishDate);
 	const trimmedContent = post.content.trim();
 	const titleMatch = trimmedContent.match(/^# (.+)$/m);
 	const title = titleMatch ? titleMatch[1] : post.frontmatter.title;