SFMS: Stations stored

**Describe the task**
When we save_sfms_run, we're storing all the station codes from the actuals. But in the processing of each parameter, we're filtering these actuals based on "valid" data. We may still not really know which stations were used for interpolating data

Ex: 289 stations saved to db, 288 stations used for temp/rh/precip/wind speed, 287 stations used for wind direction

**Acceptance Criteria**
- [ ] first
- [ ] second
- [ ] third

**Additional context**
- Add any other context about the task here.
- Or here

Start by tracing save_sfms_run and the per-parameter filtering of actual station data. Compare the stations saved to the stations actually used for temperature, relative humidity, precipitation, wind speed, and wind direction, then clarify the missing acceptance criteria so completion can be verified.

Written by the indexing model from the issue text.