fix: Use only dist folder (contains public assets)

- Astro build automatically copies public/ to dist/
- Remove separate public folder copy (not needed)
- Use PORT environment variable (default 80)
- Fix favicon 404 by using correct dist structure

astro.config.mjs

@@ -0,0 +1,11 @@
+// @ts-check
+import { defineConfig } from 'astro/config';
+
+import tailwindcss from '@tailwindcss/vite';
+
+// https://astro.build/config
+export default defineConfig({
+  vite: {
+    plugins: [tailwindcss()]
+  }
+});