Series RLC bench sweep

Open preview.html for the complete lab. Use the two matched ground-referenced
scope channels as drawn in fixture.svg. Fill observations-blank.csv from
your own bench readings. Keep every recorded frequency in both runs.

Python 3.9+ and its standard library are sufficient.
  python3 rlc_sweep.py observations.csv
  python3 rlc_sweep.py synthetic-sweep.csv --winding-dc-ohms 12
  python3 -m unittest -v test_rlc_sweep.py

The synthetic CSV, its JSON report and the response figure are calculated.
The blank worksheet contains no physical observations.
