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/vite-plugin-markdown/index.d.ts

@@ -0,0 +1,9 @@
+import type { Plugin } from 'vite';
+import type { Logger } from '../core/logger/core.js';
+import type { AstroSettings } from '../types/astro.js';
+interface AstroPluginOptions {
+    settings: AstroSettings;
+    logger: Logger;
+}
+export default function markdown({ settings, logger }: AstroPluginOptions): Plugin;
+export {};