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.

package.json

@@ -7,7 +7,8 @@
     "build": "next build",
     "start": "next start",
     "lint": "next lint",
-    "sitemap": "next-sitemap"
+    "sitemap": "ts-node scripts/generate-sitemap.ts",
+    "postbuild": "npm run sitemap"
   },
   "dependencies": {
     "axios": "^1.9.0",
@@ -25,6 +26,7 @@
     "@types/node": "^20",
     "@types/react": "^19",
     "@types/react-dom": "^19",
+    "dotenv": "^16.5.0",
     "eslint": "^9",
     "eslint-config-next": "15.3.3",
     "eslint-config-prettier": "^10.1.5",
@@ -34,6 +36,8 @@
     "prettier": "^3.5.3",
     "prettier-plugin-tailwindcss": "^0.6.12",
     "tailwindcss": "^4",
-    "typescript": "^5"
+    "ts-node": "^10.9.2",
+    "tsconfig-paths": "^4.2.0",
+    "typescript": "^5.8.3"
   }
 }