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.

demo/main.js

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+import "slatehtml";
+
+import "slatehtml-ui/icon";
+import "slatehtml-ui/side-bar";
+import "slatehtml-ui/progress";
+import "slatehtml-ui/alert";
+import "slatehtml-ui/divider";
+import "slatehtml-ui/bottom-nav";
+import "slatehtml-ui/bottom-nav-item";
+import "slatehtml-ui/collapse";
+
+import { configure } from "slatehtml-ui/configure";
+import { fontAwesomeSvg } from "slatehtml-ui/icons/fontawesome";
+import { mountDocs } from "../src/index.js";
+import "../src/prose.css";
+import "./site.css";
+
+configure({
+  icons: fontAwesomeSvg,
+  iconSize: "15",
+});
+
+await mountDocs("slate-docs-viewer", { indexUrl: "./index.json" });
+document.documentElement.setAttribute("data-ready", "");

demo/site.css

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+/* Match live Docs-Viewer tokens (lit.ruv.wtf/docs). */
+
+:root {
+  --bg: #1a1a1a;
+  --ink: #e0e0e0;
+  --muted: #a0a0a0;
+  --panel: #252526;
+  --line: #404040;
+  --accent: #2196f3;
+  --docs-accent: #2196f3;
+  --docs-panel: #252526;
+  --docs-line: #404040;
+  --docs-muted: #a0a0a0;
+  --slate-font: system-ui, -apple-system, "Segoe UI", Roboto, Ubuntu, Cantarell, "Noto Sans",
+    sans-serif;
+  --slate-font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
+  color-scheme: dark;
+}
+
+body {
+  margin: 0;
+  min-height: 100%;
+  background: var(--bg);
+  color: var(--ink);
+  font-family: var(--slate-font);
+}