Update interactive navigation

Updated the navigation links on the interactive page to "Back to Foundations" on the left and "Back to Discrete Math" on the right.

src/pages/theme-pages/discrete-math/Foundations.tsx

@@ -42,14 +42,20 @@ const Foundations = () => {
       <Layout>
         <div className="container mx-auto px-4 py-8">
           <div className="space-y-6">
-            <div className="flex items-center gap-4">
+            <div className="flex items-center justify-between">
+              <button
+                onClick={() => setSelectedInteractive(null)}
+                className="text-primary hover:text-primary/80 font-medium"
+              >
+                ← Back to Foundations
+              </button>
+              <h1 className="text-2xl font-bold text-foreground">{selectedInteractive.title}</h1>
               <Link 
                 to="/themes/discrete-math"
                 className="text-primary hover:text-primary/80 font-medium"
               >
-                ← Back to Discrete Math
+                Back to Discrete Math →
               </Link>
-              <h1 className="text-2xl font-bold text-foreground">{selectedInteractive.title}</h1>
             </div>
             <div className="bg-background border rounded-lg p-6">
               <InteractiveComponent />