feat: Implement website structure

- Add navigation with Themes, Puzzles, and Miscellany.
- Create "coming soon" pages for Puzzles and Miscellany.
- Create a Themes page with cards for various topics.
- Implement basic boxy layout.
- Prepare for future interactive additions and filtering.
- Set up for Netlify deployment.

src/pages/Puzzles.tsx

@@ -0,0 +1,12 @@
+import ComingSoon from "@/components/ComingSoon";
+
+const Puzzles = () => {
+  return (
+    <ComingSoon 
+      title="Interactive Puzzles"
+      description="Get ready for an engaging collection of educational puzzles designed to challenge your problem-solving skills and reinforce key concepts across multiple disciplines."
+    />
+  );
+};
+
+export default Puzzles;