feat: page interactive, démos Play/Step et simulateur Carnot

Ajoute le pipeline PageSpec (validation, rendu, publication /p/{slug}),
les démos TipTap /demo, et le simulateur Carnot (modes frigo/PAC/moteur,
énergie kJ vs puissance W, unités K/°C/°F) avec correctifs d’équations KaTeX.

Co-authored-by: Cursor <cursoragent@cursor.com>

memento-note/app/(main)/dev/interactive-page/page.tsx

@@ -0,0 +1,23 @@
+import { notFound } from 'next/navigation'
+import { PageView } from '@/components/interactive-page/page-view'
+import { validateInteractivePage } from '@/lib/interactive-page'
+import thermoFixture from '@/lib/interactive-page/fixtures/thermo-page.json'
+
+/**
+ * Dev preview of PageView + thermo fixture (spec §8.3).
+ * Only available outside production.
+ */
+export default function InteractivePagePreviewPage() {
+  if (process.env.NODE_ENV === 'production') notFound()
+
+  const parsed = validateInteractivePage(thermoFixture)
+  if (!parsed.ok) {
+    return (
+      <div className="p-8 text-sm text-destructive">
+        Fixture invalide : {parsed.issues[0]?.message}
+      </div>
+    )
+  }
+
+  return <PageView page={parsed.page} demoMode="interactive" />
+}