fix: import missing modules to resolve undefined name errors in firecrawl_web_crawler.py

lib/ai_web_researcher/firecrawl_web_crawler.py

@@ -1,5 +1,8 @@
 from firecrawl_client import initialize_client
 import logging
+import os
+from pathlib import Path
+from firecrawl import FirecrawlApp
 from dotenv import load_dotenv
 # Load environment variables from .env file
 load_dotenv(Path('../../.env'))