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

nixpacks.toml

@@ -0,0 +1,14 @@
+# Nixpacks Configuration for Astro
+# https://nixpacks.com/docs/configuration/file
+
+[phases.setup]
+nixPkgs = ["nodejs-20_x"]
+
+[phases.install]
+cmds = ["npm ci"]
+
+[phases.build]
+cmds = ["npm run build"]
+
+[start]
+cmd = "npm run preview -- --host 0.0.0.0 --port $PORT"