fix(mcp-webscraper): use certifi SSL context + bundled Comodo root cert

- _build_ssl_context() loads certifi bundle + all *.pem from certs/ dir
- _SSL_CTX singleton built at module load, passed to httpx.get(verify=...)
- Fixes SSLCertVerificationError on Cloudflare-served sites on Fedora 43
  (Comodo AAA root cert missing from system trust store)
- test_server.py: fix HTTPStatusError mock to include request= param

mcp/webscraper/tests/test_server.py

@@ -180,10 +180,11 @@ def test_empty_page(mock_get):
 @patch('httpx.get')
 def test_404(mock_get):
     """Test 404 response."""
+    mock_req = MagicMock()
     mock_resp = MagicMock()
     mock_resp.status_code = 404
     mock_resp.text = "Not Found"
-    mock_get.side_effect = httpx.HTTPStatusError("Client Error", response=mock_resp)
+    mock_get.side_effect = httpx.HTTPStatusError("404 Not Found", request=mock_req, response=mock_resp)
     result = webscraper_fetch("https://notfound.com")
     assert "Error fetching" in result
     assert "404" in result