Migrate @data-driven-forms/react-renderer-demo package from JavaScript to TypeScript.

Package Details:

• Package: @data-driven-forms/react-renderer-demo
• Current size: 143 JS files, 11,365 lines of code
• Purpose: Documentation and demo website built with NextJS
• Dependencies: All component mappers, react-form-renderer, common
• Priority: MEDIUM - Documentation site for consistency

Migration Tasks:

• Convert .js/.jsx files to .ts/.tsx
• Add proper TypeScript type definitions for demo components
• Type all NextJS page components and API routes
• Update React component props with proper TypeScript types
• Ensure demo examples have proper type safety
• Update imports/exports to use TypeScript types
• Update NextJS configuration for TypeScript if needed
• Run tests to ensure demo site works correctly
• Update any generated type definitions to source types

Technical Notes:

• Should be migrated after all other packages are completed
• Documentation site - good for demonstrating TypeScript usage
• TypeScript infrastructure already configured
• Must ensure all demos continue to work properly

Repository: https://github.com/data-driven-forms/react-forms
Package Path: packages/react-renderer-demo/