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/core/shiki.d.ts

@@ -0,0 +1,2 @@
+import { type ShikiConfig, type ShikiHighlighter } from '@astrojs/markdown-remark';
+export declare function getCachedHighlighter(opts: ShikiConfig): Promise<ShikiHighlighter>;