Redesign site and streamline playground

site/decodal-site/src/lib/docs.js

@@ -94,6 +94,17 @@ export function allDocSlugs() {
   return Object.keys(docs).filter((slug) => slug !== 'index');
 }
 
+export function docTitle(slug, items = nav) {
+  for (const item of items) {
+    if (item.slug === slug) return item.title;
+    if (item.children) {
+      const childTitle = docTitle(slug, item.children);
+      if (childTitle) return childTitle;
+    }
+  }
+  return slug;
+}
+
 export function renderMarkdown(slug) {
   const source = docs[slug] ?? docs.index;
   const html = marked.parse(source ?? '# Not found\n');