Refactor: rename SimDUT, restructure DUT simulation and test flow

tests/test_dut.py

@@ -0,0 +1,14 @@
+# tests/test_dut.py
+
+import pytest
+
+def test_dut_version(dut):
+    """Ensure the DUT returns a version string in sim mode."""
+    version = dut.get_version()
+    assert version.startswith("sim-")
+
+def test_dut_temperature(dut):
+    """Test readback of simulated temperature."""
+    temp = dut.read_temperature()
+    assert 20 <= temp <= 100  # Acceptable range
+