feat(examples): add saas tutorial skeleton

Add a compile-tested v1 tutorial skeleton that proves the production-shaped app boundary without provider-heavy scope: auth/session context, CSRF-checked mutation, local persistence adapter, generated form/slot/keyed row/page/push effects, plain CSS, SSE shape, and one explicit metrics island.

req: examples/001

req: auth/001

req: auth/002

req: auth/004

req: form/001

req: failure/004

req: page_swap/002

req: push/003

examples/saas/templates/metrics.js

@@ -0,0 +1,14 @@
+(() => {
+  function render(island) {
+    const count = island.getAttribute("data-project-count") || "0";
+    const readout = island.querySelector("[data-island-readout]");
+    if (readout) readout.textContent = `${count} persisted project${count === "1" ? "" : "s"}`;
+  }
+
+  function boot() {
+    for (const island of document.querySelectorAll('[data-hemx-island="metrics"]')) render(island);
+  }
+
+  document.addEventListener("DOMContentLoaded", boot);
+  document.addEventListener("hemx:after-settle", boot);
+})();