fix(ci): resolve JSCPD duplicate and spell-check failures

- Consolidate two near-identical conftest files into tests/conftest.py
  to fix JSCPD copy-paste detection failure
- Add ASSRF, canonname, gaierror, IMDS, INJ, sockaddr to spell-check
  allow list (all come from our url_validation.py patch)

Author: amit-raut

.github/actions/spelling/allow.txt

@@ -94,3 +94,9 @@ Tful
 tiangolo
 typeerror
 vulnz
+ASSRF
+canonname
+gaierror
+IMDS
+INJ
+sockaddr

tests/client/conftest.py

@@ -0,0 +1,17 @@
+import pytest
+from unittest.mock import patch
+
+
+@pytest.fixture(autouse=True)
+def bypass_ssrf_url_validation(request):
+    """Bypass DNS-based SSRF validation for all tests except test_url_validation.
+
+    Most tests use synthetic hostnames (localhost, testserver, example.com)
+    that either resolve to loopback or are unavailable in CI. The actual SSRF
+    validation logic is tested in tests/utils/test_url_validation.py.
+    """
+    if "test_url_validation" in request.node.nodeid:
+        yield
+    else:
+        with patch("a2a.client.card_resolver.validate_agent_card_url"):
+            yield