feat: Replace Next.js with Astro + PDPA compliance

- Removed Next.js, moved Astro to root
- PDPA compliance: cookie consent, admin dashboard, privacy policy
- Updated Dockerfile for Astro
- Ready for Easypanel deployment with Nixpacks or Docker

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()]
+  }
+});