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/vite-plugin-head/index.d.ts

@@ -0,0 +1,5 @@
+import type * as vite from 'vite';
+import type { BuildInternals } from '../core/build/internal.js';
+import type { AstroBuildPlugin } from '../core/build/plugin.js';
+export default function configHeadVitePlugin(): vite.Plugin;
+export declare function astroHeadBuildPlugin(internals: BuildInternals): AstroBuildPlugin;