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

.docker/Dockerfile

@@ -0,0 +1,14 @@
+# Astro Production Dockerfile
+FROM node:20-alpine
+
+WORKDIR /app
+
+COPY package*.json ./
+RUN npm ci --omit=dev
+
+COPY . .
+RUN npm run build
+
+EXPOSE 4321
+
+CMD ["npm", "run", "preview", "--", "--host", "0.0.0.0", "--port", "4321"]