Port Docs-Viewer to slatehtml as the docs-viewer package.

Replace the classic DOM shell with slate widgets, markdown→slate rendering, and a CI index build that uses build-docs.cjs.

src/markdown/decorate.js

@@ -0,0 +1,24 @@
+/**
+ * Light post-pass for marked HTML: wiki `?slug` links + lazy images.
+ * Content is trusted site markdown — no tag stripping.
+ */
+
+export function decorateHtml(html) {
+  if (!html) return "";
+  if (typeof document === "undefined") return String(html);
+
+  const tpl = document.createElement("template");
+  tpl.innerHTML = String(html);
+  for (const a of tpl.content.querySelectorAll("a[href]")) {
+    const href = a.getAttribute("href") || "";
+    if (href.startsWith("?")) a.setAttribute("data-internal", "true");
+    else if (href.startsWith("http")) {
+      a.setAttribute("target", "_blank");
+      a.setAttribute("rel", "noopener noreferrer");
+    }
+  }
+  for (const img of tpl.content.querySelectorAll("img:not([loading])")) {
+    img.setAttribute("loading", "lazy");
+  }
+  return tpl.innerHTML;
+}