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/partials/project_row.heml

@@ -0,0 +1,4 @@
+<li class="project-row" +data-key="self.id">
+  <strong>{+ self.name +}</strong>
+  <span>{+ self.owner +}</span>
+</li>

examples/saas/templates/partials/settings_page.heml

@@ -0,0 +1,4 @@
+<section class="settings-page">
+  <h2>Settings</h2>
+  <p>{+ self.message +}</p>
+</section>