Refactor site structure and add comprehensive interactive index

- Move Puzzles and Miscellany under Themes
- Add Contest Problems as new theme
- Create About page with comprehensive site information
- Create InteractiveIndex component with advanced filtering and sorting
- Update navigation to include Index, Themes, and About
- Add pagination (10 items per page) with search and tag filtering
- Update routing structure for new theme organization
- Remove standalone Puzzles and Miscellany pages
- Add new theme pages: /themes/puzzles, /themes/miscellany, /themes/contest-problems
- Update homepage to point to new interactive index
- Maintain consistent layout and styling across all new pages

src/pages/Themes.tsx

@@ -6,7 +6,10 @@ import {
   Database, 
   Gamepad2, 
   CreditCard,
-  Calculator
+  Calculator,
+  Puzzle,
+  Sparkles,
+  Trophy
 } from "lucide-react";
 import Layout from "@/components/Layout";
 import ThemeCard from "@/components/ThemeCard";
@@ -48,6 +51,24 @@ const Themes = () => {
       description: "Discover mathematical principles and probability theory through card games and interactive demonstrations.",
       path: "/themes/cards-math",
       icon: <CreditCard className="w-6 h-6" />
+    },
+    {
+      title: "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.",
+      path: "/themes/puzzles",
+      icon: <Puzzle className="w-6 h-6" />
+    },
+    {
+      title: "Miscellany",
+      description: "Discover unique educational experiments, creative tools, and innovative interactive content that doesn't fit into traditional categories but sparks curiosity and enhances learning.",
+      path: "/themes/miscellany",
+      icon: <Sparkles className="w-6 h-6" />
+    },
+    {
+      title: "Contest Problems",
+      description: "Practice with problems from programming competitions, mathematical olympiads, and algorithmic challenges with interactive solutions and explanations.",
+      path: "/themes/contest-problems",
+      icon: <Trophy className="w-6 h-6" />
     }
   ];