feat(simulation): stabilize IPC layer and verify full workflow

tests/conftest.py

@@ -32,11 +32,15 @@ def live_gui():
     """
     print("\n[Fixture] Starting gui.py --enable-test-hooks...")
     
+    # Ensure logs directory exists
+    os.makedirs("logs", exist_ok=True)
+    log_file = open("logs/gui_test.log", "w", encoding="utf-8")
+
     # Start gui.py as a subprocess.
     process = subprocess.Popen(
         ["uv", "run", "python", "gui.py", "--enable-test-hooks"],
-        stdout=subprocess.DEVNULL,
-        stderr=subprocess.DEVNULL,
+        stdout=log_file,
+        stderr=log_file,
         text=True,
         creationflags=subprocess.CREATE_NEW_PROCESS_GROUP if os.name == 'nt' else 0
     )