fix(og): match Eleventy's page.fileSlug by stripping date prefix

Eleventy v3 parses YYYY-MM-DD- from filenames and removes it from
page.fileSlug. The OG generator was using the full filename (with
date prefix) causing a slug mismatch — hasOgImage filter checked
for 'slug.png' while the file was 'YYYY-MM-DD-slug.png'.

Also removes debug logging from hasOgImage filter.

lib/og.js

@@ -105,6 +105,14 @@ function formatDate(dateStr) {
   }
 }
 
+/**
+ * Strip YYYY-MM-DD- date prefix from filename to match Eleventy's page.fileSlug.
+ * Eleventy v3 parses dates from filenames and removes the prefix from fileSlug.
+ */
+function toEleventySlug(filename) {
+  return filename.replace(/^\d{4}-\d{2}-\d{2}-/, "");
+}
+
 function truncateTitle(title, max = 120) {
   if (!title || title.length <= max) return title || "Untitled";
   return title.slice(0, max).trim() + "\u2026";
@@ -299,7 +307,7 @@ export async function generateOgImages(contentDir, cacheDir, siteName) {
       continue;
     }
 
-    const slug = basename(filePath, ".md");
+    const slug = toEleventySlug(basename(filePath, ".md"));
     const title = fm.title || fm.name || extractBodyText(raw);
     const date = fm.published || fm.date || "";
     const postType = detectPostType(filePath);