feat(simulation): implement UserSimAgent for human-like interaction

tests/test_user_agent.py

@@ -0,0 +1,22 @@
+import pytest
+import sys
+import os
+
+# Ensure project root is in path for imports
+sys.path.append(os.path.abspath(os.path.join(os.path.dirname(__file__), "..")))
+
+from simulation.user_agent import UserSimAgent
+
+def test_user_agent_instantiation():
+    agent = UserSimAgent(hook_client=None)
+    assert agent is not None
+
+def test_perform_action_with_delay():
+    agent = UserSimAgent(hook_client=None)
+    called = False
+    def action():
+        nonlocal called
+        called = True
+    
+    agent.perform_action_with_delay(action)
+    assert called is True