feat: implement platform management system with authentication and dashboard

- Add PlatformUser model with roles (SUPER_ADMIN, ADMIN, SUPPORT)
- Implement platform authentication with NextAuth
- Create platform dashboard showing companies, users, and sessions
- Add platform API endpoints for company management
- Update landing page with SaaS design
- Include test improvements and accessibility updates

app/platform/layout.tsx

@@ -0,0 +1,15 @@
+"use client";
+
+import { SessionProvider } from "next-auth/react";
+
+export default function PlatformLayout({
+  children,
+}: {
+  children: React.ReactNode;
+}) {
+  return (
+    <SessionProvider>
+      {children}
+    </SessionProvider>
+  );
+}