feat: Upgrade to Astro with full PDPA compliance

PDPA Features:
✅ Cookie consent banner
✅ Consent logging API
✅ Admin dashboard
✅ Privacy Policy
✅ Terms & Conditions

Technical:
✅ Astro 5.x + Tailwind v4
✅ Docker on port 80
✅ SQLite database
✅ 15 pages built

Ready for Easypanel deployment.

node_modules/retext-stringify/lib/index.d.ts

@@ -0,0 +1,8 @@
+/**
+ * Add support for serializing natural language.
+ *
+ * @returns {undefined}
+ *   Nothing.
+ */
+export default function retextStringify(): undefined;
+export type Root = import('nlcst').Root;