✨ feat: add Vercel deployment support and optimize build configuration

Configure project for Vercel deployment with comprehensive build optimization:

- Add Vercel deployment configuration (vercel.json)
  - Configure build commands and output directory
  - Set up Bilibili API proxy rewrites
  - Add security response headers (X-Content-Type-Options, X-Frame-Options, X-XSS-Protection)

- Integrate Tailwind CSS 4.x build system
  - Add PostCSS configuration with @tailwindcss/postcss plugin
  - Create Tailwind CSS configuration with content scanning paths
  - Set up index.css with Tailwind imports and custom styles
  - Add Tailwind CSS 4.x and dependencies to package.json

- Optimize HTML and entry files
  - Remove CDN-based Tailwind CSS in favor of local build
  - Add Google Fonts preconnect for better performance
  - Import CSS in index.tsx for proper bundling

- Update README with deployment instructions
  - Add one-click Vercel deployment button
  - Separate local development and deployment sections

Tech Stack Updates:
- Tailwind CSS 4.1.17 with new PostCSS architecture
- Autoprefixer 10.4.22 for CSS compatibility
- PostCSS 8.5.6 for CSS processing

Build Verification:
- Development server runs successfully on port 3000
- Production build completes in ~860ms
- Output: 13KB CSS (gzipped: 2.94KB), 260KB JS (gzipped: 80KB)

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

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

tailwind.config.ts

@@ -0,0 +1,12 @@
+import type { Config } from 'tailwindcss'
+
+export default {
+  content: [
+    "./index.html",
+    "./*.{js,ts,jsx,tsx}",
+    "./components/**/*.{js,ts,jsx,tsx}",
+    "./context/**/*.{js,ts,jsx,tsx}",
+    "./i18n/**/*.{js,ts,jsx,tsx}",
+    "./utils/**/*.{js,ts,jsx,tsx}",
+  ],
+} satisfies Config