fix: use BACKEND_PORT env var in uvicorn and honor base_url arg in searxSearch

- api.py: uvicorn.run was hardcoding port=7777 instead of using the
  port variable populated from BACKEND_PORT env var, making BACKEND_PORT
  ineffective when running python api.py directly
- searxSearch: add missing 'import sys' (caused NameError when run as
  standalone script) and use constructor base_url arg with env var
  fallback so searxSearch(base_url=...) actually takes effect

sources/tools/searxSearch.py

@@ -1,5 +1,6 @@
 import requests
 from bs4 import BeautifulSoup
+import sys
 import os
 
 if __name__ == "__main__": # if running as a script for individual testing
@@ -16,7 +17,7 @@ class searxSearch(Tools):
         self.tag = "web_search"
         self.name = "searxSearch"
         self.description = "A tool for searching a SearxNG for web search"
-        self.base_url = os.getenv("SEARXNG_BASE_URL")  # Requires a SearxNG base URL
+        self.base_url = base_url or os.getenv("SEARXNG_BASE_URL")  # Requires a SearxNG base URL
         self.user_agent = "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36"
         self.paywall_keywords = [
             "Member-only", "access denied", "restricted content", "404", "this page is not working"