fix: Resolve Tailwind CSS v4/v3 compatibility issues for deployment

- Downgrade @astrojs/tailwind to v5.1.1 for v3 compatibility
- Remove @tailwindcss/vite dependency (v4 specific)
- Update tailwindcss to v3.4.17
- Fix astro.config.mjs to use standard Tailwind integration
- Update CSS imports to use v3 @tailwind directives

Fixes server deployment build failures due to dependency conflicts.

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

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

src/styles/global.css

@@ -1,4 +1,6 @@
-@import "tailwindcss";
+@tailwind base;
+@tailwind components;
+@tailwind utilities;
 @import "./glassmorphism.css";
 
 /* Accessibility Styles */