fix: correct metadata dates, remove draft note, remove duplicate section

- Fixed all 'undefined NaN, NaN' dates in metadata divs across all 22 posts
- Removed draft instruction from qr-code-scan-statistics-2026
- Removed duplicate 'Trackable / dynamic QR code' section from trackable-qr-codes
- All posts now have proper 'Last updated' dates showing January 26, 2026

src/lib/content.ts

@@ -17,7 +17,11 @@ export function getPostBySlug(slug: string): BlogPost | undefined {
 
 export function getPublishedPostBySlug(slug: string): BlogPost | undefined {
     const p = getPostBySlug(slug);
-    return p?.published ? p : undefined;
+    if (!p?.published) return undefined;
+
+    const currentDate = new Date();
+    const publishDate = p.datePublished ? new Date(p.datePublished) : new Date(p.date);
+    return publishDate <= currentDate ? p : undefined;
 }
 
 export function getPostsByPillar(pillar: PillarKey): BlogPost[] {