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/cli/throw-and-exit.d.ts

@@ -0,0 +1,2 @@
+/** Display error and exit */
+export declare function throwAndExit(cmd: string, err: unknown): Promise<void>;