fix return-value/deprecated API bugs, accumulation lock leaks, code cleanup

- raise instead of silent None for unsupported operands and empty negation
- validate before acquiring lock in Accumulation operators (no RLock leak)
- Accumulation._copy_provenance helper, ADC_Result._copy_metadata for all result paths
- shared _sandbox_stdout_redirect contextmanager for sandboxed scripts
- TemperatureMonitor dead code removal (gtk helper, traceback, unused properties)
- new unit tests incl. lock-freedom regression test
- gitignore sphinx generated doc/_autosummary/ and doc/damaris/

tests/test_MeasurementResult.py

@@ -0,0 +1,35 @@
+import unittest
+
+import numpy as np
+
+from damaris.data.MeasurementResult import MeasurementResult
+
+
+class TestMeasurementResult(unittest.TestCase):
+    def test_add_zero_preserves_data(self):
+        """mr + 0 must return a MeasurementResult with identical data."""
+        mr = MeasurementResult("test_quantity")
+        for i in range(3):
+            mr[i] = float(i * i)
+        mr2 = mr + 0
+        self.assertIsInstance(mr2, MeasurementResult)
+        self.assertEqual(mr2.quantity_name, "test_quantity")
+        np.testing.assert_array_equal(mr2.get_xdata(), mr.get_xdata())
+        np.testing.assert_array_equal(mr2.get_ydata(), mr.get_ydata())
+
+    def test_add_zero_returns_independent_copy(self):
+        """Changing the copy must not change the original."""
+        mr = MeasurementResult("q")
+        mr[1.0] = 5.0
+        mr2 = mr + 0
+        self.assertIsNot(mr2[1.0], mr[1.0])
+        mr2[1.0] = mr2[1.0] + 100.0
+        self.assertEqual(mr[1.0].mean(), 5.0)
+
+    def test_add_nonzero_raises(self):
+        mr = MeasurementResult("q")
+        self.assertRaises(Exception, mr.__add__, 1)
+
+
+if __name__ == "__main__":
+    unittest.main()