refactor: Move Astro to root, use PORT env (default 80), allow all hosts

- Move Astro files from dealplustech-astro/ to project root
- Update Dockerfile: PORT environment variable (default 80)
- Add vite.config.ts with allowedHosts: true
- Matches nixpacks behavior for Easypanel deployment
- No hardcoded ports or domains

node_modules/astro/dist/manifest/virtual-module.d.ts

@@ -0,0 +1,5 @@
+import type { Plugin } from 'vite';
+import type { SSRManifest } from '../types/public/index.js';
+export default function virtualModulePlugin({ manifest }: {
+    manifest: SSRManifest;
+}): Plugin;