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/main.ts

@@ -0,0 +1,42 @@
+/**
+ * HOMECORE frontend entry point.
+ * Imports global styles, registers Lit components, and mounts the app shell.
+ */
+
+import './styles/tokens.css';
+import './styles/base.css';
+
+// Register custom elements
+import './components/AppShell.js';
+import './components/StateCard.js';
+import './pages/Dashboard.js';
+import './pages/States.js';
+import './pages/Services.js';
+import './pages/Settings.js';
+
+// Tiny router: the AppShell dispatches `hc-navigate` on every nav
+// click. We swap whichever page element is sitting in its <slot>
+// based on the new active id. Default page on first paint = dashboard.
+const NAV_TO_TAG: Record<string, string> = {
+    dashboard: 'hc-dashboard',
+    states: 'hc-states',
+    services: 'hc-services',
+    settings: 'hc-settings',
+};
+
+function mountPage(shell: Element, tag: string): void {
+    // Remove any existing page (everything that isn't itself the shell).
+    Array.from(shell.children).forEach((c) => c.remove());
+    shell.appendChild(document.createElement(tag));
+}
+
+window.addEventListener('DOMContentLoaded', () => {
+    const shell = document.querySelector('hc-app-shell');
+    if (!shell) return;
+    mountPage(shell, 'hc-dashboard');
+    shell.addEventListener('hc-navigate', (ev) => {
+        const id = (ev as CustomEvent<{ id: string }>).detail?.id;
+        const tag = id ? NAV_TO_TAG[id] : undefined;
+        if (tag) mountPage(shell, tag);
+    });
+});