fix: only target text links for 'internal' class prepend

prepends/link.typ

@@ -3,9 +3,26 @@
 #show link: it => {
   let dest = it.dest
   if type(dest) == str {
+    // Check if body is text-only (no images or other non-text elements)
+    let is-text-only(content) = {
+      let sequence = [a b].func()
+      let allowed = (text, strong, emph)
+      if content.func() == text { return true }
+      if content.func() in allowed {
+        if content.has("body") {
+          return is-text-only(content.body)  // recurse into strong/emph
+        }
+        return true
+      }
+      if content.func() == sequence {
+        return content.children.all(c => is-text-only(c))
+      }
+      false
+    }
+
     let is-internal = dest.starts-with("/") or dest.starts-with(".")
     let attrs = (href: dest)
-    if is-internal {
+    if is-internal and is-text-only(it.body) {
       attrs = (href: dest, class: "internal")
     }
     html.elem("a", attrs: attrs, it.body)