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/

src/damaris/data/DamarisFFT.py

@@ -19,10 +19,6 @@ class DamarisFFT:
         :param float stop: end of clipping in s
 
         """
-        # check if start/stop order is properly
-        if start > stop:
-            start, stop = stop, start
-
         # do nothing if one uses clip as a "placeholder"
         if start is None and stop is None:
             return self
@@ -32,6 +28,10 @@ class DamarisFFT:
         if stop is None:
             stop = self.x[ -1 ]
 
+        # check if start/stop order is properly
+        if start > stop:
+            start, stop = stop, start
+
         # check if data is fft which changes the start/stop units
         if self.xlabel == "Frequency / Hz":
             start = self.x.size * (0.5 + start / self.sampling_rate)