refactor(react): replace tsup with rollup for proper CSS modules support

- Replace tsup build system with rollup + postcss for better CSS modules handling
- Add rollup.config.js with proper CSS modules configuration
- Add TypeScript build config (tsconfig.build.json) for declarations
- Add CSS modules type definitions (src/types.d.ts)
- Update react-demo to import CSS file alongside components
- Fix CSS injection issue where styles weren't being applied in development

The new build system properly processes CSS modules and generates hashed class names
while ensuring styles are correctly applied when importing MediaSkinDefault.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

examples/react-demo/src/main.tsx

@@ -1,6 +1,7 @@
 import React from 'react';
 import ReactDOM from 'react-dom/client';
 import { MediaProvider, Video, MediaSkinDefault } from '@vjs-10/react';
+import '@vjs-10/react/style.css';
 
 const DemoPlayer = () => {
   return (