fix: mock config in test_init_defaults to test class-level defaults

The test_init_defaults test expected OperativeAgent class defaults
(temperature=0.3) but didn't mock load_config(), so when config loaded
successfully it returned the global default (0.7) instead.

Fix: mock load_config to raise, so the test properly validates the
class-level _default_temperature/max_tokens/max_turns fallback path.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/operators/test_operators.py

@@ -485,7 +485,11 @@ class TestOperativeAgent:
         from openjarvis.agents.operative import OperativeAgent
 
         engine = FakeEngine()
-        agent = OperativeAgent(engine, "test-model")
+        with patch(
+            "openjarvis.agents._stubs.load_config",
+            side_effect=Exception("no config"),
+        ):
+            agent = OperativeAgent(engine, "test-model")
         assert agent.agent_id == "operative"
         assert agent._temperature == 0.3
         assert agent._max_tokens == 2048