Add ToDo-Karten product page, fluid design tokens, and Navbar/Hero fixes

New /todo-cards page (Hero, How-it-works, Focus, Testimonials, Pricing)
built with the fluid clamp() token system (app/lib/fluid.ts) and
scroll-reveal animations (app/components/Reveal.tsx), matching styling
consistency with /challenge's testimonial section.

Navbar: page-aware active state and anchor-link navigation from any
route (not just "/"), fixed logo click to actually navigate instead of
silently rewriting the URL, fluid nav text size, custom hash-scroll
handling for cross-page anchor links.

Hero: responsive breakpoint fix for the text/image split at Tablet
widths, entrance animation for the brand's orange dot, removed a red
dot artifact from hero.png.

Also includes prior uncommitted work on About/Blog/Newsletter/Footer
and the cart lib (app/lib/cart.ts).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/todo-cards/page.tsx

@@ -0,0 +1,45 @@
+import type { Metadata } from "next";
+import { TodoKartenHero } from "./components/TodoKartenHero";
+import { HowItWorks } from "./components/HowItWorks";
+import { Focus } from "./components/Focus";
+import { Testimonials } from "./components/Testimonials";
+import { Pricing } from "./components/Pricing";
+import { Footer } from "../components/Footer";
+
+const title = "ToDo-Karten – Kleine Karten. Große Wirkung.";
+const description =
+  "Ein einfaches Werkzeug, das dir hilft, deinen Kopf frei zu bekommen und das Wesentliche zu sehen. 50 hochwertige ToDo-Karten für mehr Fokus im Alltag.";
+
+export const metadata: Metadata = {
+  title,
+  description,
+  alternates: {
+    canonical: "/todo-cards",
+  },
+  openGraph: {
+    title,
+    description,
+    url: "/todo-cards",
+    images: ["/hero-todo-karten.png"],
+  },
+  twitter: {
+    title,
+    description,
+    images: ["/hero-todo-karten.png"],
+  },
+};
+
+export default function TodoCardsPage() {
+  return (
+    <>
+      <main className="flex flex-col flex-1">
+        <TodoKartenHero />
+        <HowItWorks />
+        <Focus />
+        <Testimonials />
+        <Pricing />
+      </main>
+      <Footer />
+    </>
+  );
+}