Fix Tailwind config: add @tailwindcss/vite plugin and use bun server for production

- Add @tailwindcss/vite plugin for proper Tailwind processing
- Change 'start' script from 'vite preview' to 'bun server.ts' (production-ready)
- Remove postcss.config.mjs (handled by Vite plugin)
- server.ts already configured to serve from dist/ directory

Co-Authored-By: Claude Sonnet 4.5 (1M context) <noreply@anthropic.com>

vite.config.ts

@@ -1,8 +1,9 @@
 import { defineConfig } from 'vite'
 import react from '@vitejs/plugin-react'
+import tailwindcss from '@tailwindcss/vite'
 
 export default defineConfig({
-  plugins: [react()],
+  plugins: [react(), tailwindcss()],
   server: {
     port: 3001,
     proxy: {