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

package.json

@@ -14,6 +14,7 @@
     "prisma:generate": "prisma generate",
     "prisma:migrate": "prisma migrate dev",
     "prisma:seed": "tsx prisma/seed.ts",
+    "prisma:seed:platform": "tsx prisma/seed-platform.ts",
     "prisma:push": "prisma db push",
     "prisma:push:force": "prisma db push --force-reset",
     "prisma:studio": "prisma studio",