JP-4282: Flag group 0 snowballs

[melanieclarke]

Resolves JP-4282

Allow snowballs that occur in group 0 to be flagged. The fix is to start iterating at group 0 instead of 1, and take the "previous" group DQ value to be all-zero.

Associated jwst PR to do the same for zeroframes: spacetelescope/jwst#10838

Tasks

• update or add relevant tests
• update relevant docstrings and / or docs/ page
• Does this PR change any API used downstream? (if not, label with no-changelog-entry-needed)
  • write news fragment(s) in changes/: echo "changed something" > changes/<PR#>.<changetype>.rst (see changelog readme for instructions)
  • if your change breaks existing functionality, also add a changes/<PR#>.breaking.rst news fragment
• run regression tests with this branch installed ("git+https://github.com/<fork>/stcal@<branch>")
  • jwst regression test
  • romancal regression test

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.92%. Comparing base (28c2283) to head (5c8d9f6).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #566   +/-   ##
=======================================
  Coverage   91.91%   91.92%           
=======================================
  Files          63       63           
  Lines        8920     8925    +5     
=======================================
+ Hits         8199     8204    +5     
  Misses        721      721           

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[melanieclarke]

jwst regtests:
https://github.com/spacetelescope/RegressionTests/actions/runs/31017446484
Expected diffs in detector1.

romancal regtests:
https://github.com/spacetelescope/RegressionTests/actions/runs/31018259887
All passing.

[melanieclarke]

Running the jwst regtests locally and spot checking the changes, the diffs look to me like improvements to isolated snowballs, similar to the example mentioned in the ticket.

For example, for jw01094001002_02107_00001_nis_rate.fits from the NIRISS imaging regression test, a snowball around x,y = 838,490 that saturates in the first group is now caught and masked:

[melanieclarke]

Rerunning regtests and moving this to ready for review.

jwst: https://github.com/spacetelescope/RegressionTests/actions/runs/33526380596
Diffs as expected in detector1 products.

romancal: https://github.com/spacetelescope/RegressionTests/actions/runs/33512584960
All passing.

[melanieclarke]

Setting this back to draft again. It needs more investigation, for zeroframe handling.

Edit: done. Needs a jwst PR: spacetelescope/jwst#10838

[melanieclarke]

@schlafly - can you review for Roman?