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/mdast-util-to-markdown/lib/util/encode-character-reference.js

@@ -0,0 +1,11 @@
+/**
+ * Encode a code point as a character reference.
+ *
+ * @param {number} code
+ *   Code point to encode.
+ * @returns {string}
+ *   Encoded character reference.
+ */
+export function encodeCharacterReference(code) {
+  return '&#x' + code.toString(16).toUpperCase() + ';'
+}