BUG - CoDICE - lo-partial-densities should handle FILLVAL on input (Phase D)

[jtniehof]

Description of the issue

The l3_lo-partial-densities files are all highly negative because there is fill on the L2 input.

Steps to reproduce the issue

imap_l3_data_processor.py --instrument codice --data-level l3a --descriptor lo-partial-densities --start-date 20260118 --version v900 --dependency imap_codice_l3a_lo-partial-densities-dfa157d1_20260118_v001.json

Expected vs Actual behavior

Fill values (-1e31) on the L2 input should be ignored (most likely treated as nan); they appear to be treated as valid data.

Code Snippet (If applicable)

Additional notes, affected areas, and suggested fixes

Updating CodiceLoL2SWSpeciesData.read_from_cdf in codice/l3/lo/models.py to use read_numeric_variable for all variables hplus through fe_hiq seems to work on the surface:

energy_per_charge=cdf["energy_per_charge"][...],
hplus=read_numeric_variable(cdf["hplus"]),
...
fe_hiq=read_numeric_variable(cdf["fe_hiq"]),
data_quality=cdf["data_quality"][...],

But I only did a chunk check of the output, no unit testing or checking for side effects.

[pleasant-menlo]

Wrote code for this, still need to build container and deploy to production.