Add dotenv package for environment variable management and update pnpm-lock.yaml. Adjust layout in RegisterPage and LoginPage components for improved responsiveness. Enhance AdminPanel with ChallengeManagement section and update navigation links for challenges. Refactor Prisma schema to include Challenge model and related enums.

components/navigation/Navigation.tsx

@@ -113,6 +113,21 @@ export default function Navigation({
           >
             LEADERBOARD
           </Link>
+          {isAuthenticated && (
+            <Link
+              href="/challenges"
+              className="transition text-xs font-normal uppercase tracking-widest"
+              style={{ color: "var(--foreground)" }}
+              onMouseEnter={(e) =>
+                (e.currentTarget.style.color = "var(--accent-color)")
+              }
+              onMouseLeave={(e) =>
+                (e.currentTarget.style.color = "var(--foreground)")
+              }
+            >
+              DÉFIS
+            </Link>
+          )}
           {isAdmin && (
             <Link
               href="/admin"
@@ -271,6 +286,22 @@ export default function Navigation({
               >
                 LEADERBOARD
               </Link>
+              {isAuthenticated && (
+                <Link
+                  href="/challenges"
+                  onClick={() => setIsMenuOpen(false)}
+                  className="transition text-xs font-normal uppercase tracking-widest py-2"
+                  style={{ color: "var(--foreground)" }}
+                  onMouseEnter={(e) =>
+                    (e.currentTarget.style.color = "var(--accent-color)")
+                  }
+                  onMouseLeave={(e) =>
+                    (e.currentTarget.style.color = "var(--foreground)")
+                  }
+                >
+                  DÉFIS
+                </Link>
+              )}
               {isAdmin && (
                 <Link
                   href="/admin"