feat: front-matter image accepts {{media:...}} (S3 hero photos consistent with body)

app/src/content.go

@@ -221,6 +221,8 @@ func (c *Content) loadFile(full string) (*Article, error) {
 	// resolve {{media:...}} and {{embed:...}} shortcodes in the SOURCE first,
 	// so they also work inside markdown links ![...]({{media:x}})
 	bodyText = resolveShortcodes(bodyText, c.MediaBase)
+	// allow {{media:...}} in front-matter too (hero/cover image from S3)
+	a.FM.Image = resolveMedia(a.FM.Image, c.MediaBase)
 
 	// render markdown -> html
 	a.BodyHTML, err = c.renderMarkdown(bodyText)