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/is-inside-container/cli.js

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+import process from 'node:process';
+import isInsideContainer from './index.js';
+
+process.exitCode = isInsideContainer() ? 0 : 2;