refactor: move frontend/ to examples/frontend/

The Lit + Vite HOMECORE web UI is an example consumer of the
sensing stack, not a top-level deliverable — relocate it under
examples/ alongside the other sensor and dashboard demos.

Add an entry to examples/README.md so it's discoverable.

Co-Authored-By: claude-flow <ruv@ruv.net>

examples/frontend/src/icons/lucide.ts

@@ -0,0 +1,39 @@
+/**
+ * Minimal Lucide icon wrapper.
+ * Import only the icons used by HOMECORE components — Vite tree-shakes the rest.
+ */
+
+export {
+  Activity,
+  BarChart3,
+  Book,
+  ChevronRight,
+  Grid2X2,
+  Home,
+  LayoutDashboard,
+  Settings,
+  Shield,
+  Sun,
+  Wifi,
+  Zap,
+} from 'lucide';
+
+/** Re-export the icon node type for consumers that need it. */
+export type { IconNode as LucideIconNode } from 'lucide';
+
+/**
+ * Render a Lucide icon as an SVG string suitable for Lit's `unsafeHTML`.
+ * Each icon is 24×24, no fill, stroke = currentColor, stroke-width = 2.
+ */
+export function iconSvg(
+  paths: string,
+  { size = 24, label }: { size?: number; label?: string } = {},
+): string {
+  const ariaAttrs = label
+    ? `role="img" aria-label="${label}"`
+    : `aria-hidden="true"`;
+  return `<svg xmlns="http://www.w3.org/2000/svg" width="${size}" height="${size}"
+    viewBox="0 0 24 24" fill="none" stroke="currentColor"
+    stroke-width="2" stroke-linecap="round" stroke-linejoin="round"
+    ${ariaAttrs}>${paths}</svg>`;
+}