feat: update product categories data structure and implement sitemap generation

- Refactored product categories to use a new data structure.
- Updated API routes to fetch product categories from the new data source.
- Implemented sitemap generation script using dotenv for environment variables.
- Added sitemap generation endpoint to the API.
- Removed old sitemap file and replaced it with a dynamically generated one.

src/models/api.d.ts

@@ -0,0 +1,13 @@
+export interface APIProductCategoryEntity {
+  id: string;
+  title: string;
+  fa_title?: string;
+  icon: string;
+  typesCount: number;
+  priceTypeTitle: string;
+  fa_priceTypeTitle?: string;
+  bestForTitle: string;
+  fa_bestForTitle?: string;
+  fa_description?: string;
+  description?: string;
+}