Add calibration.py and force auto integration in spectrometer.py

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

spectrometer.py

@@ -16,6 +16,7 @@ def measure():
     dev = HPCS6500(port)
     try:
         dev.identify()
+        dev.set_integration_time(0)  # auto
         reading = dev.take_reading(psu=False)
     finally:
         dev.close()