PSF data model

[jemorrison]

Supports JP-251 Resolves RCAL-nnnn

This PR adds a PSF reference data model to support PSF-based extraction in the JWST pipeline.

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 below for change types)
  • [ ] run jwst regression tests with this branch installed ("git+https://github.com/<fork>/stdatamodels@<branch>")

news fragment change types...

- ``changes/.feature.rst``: new feature - ``changes/.bugfix.rst``: fixes an issue - ``changes/.doc.rst``: documentation change - ``changes/.removal.rst``: deprecation or removal of public API - ``changes/.misc.rst``: infrastructure or miscellaneous change

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 67.55%. Comparing base (fd6be8d) to head (dbfad48). Report is 9 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #336 +/- ## ========================================== + Coverage 66.55% 67.55% +1.00% ========================================== Files 102 115 +13 Lines 5456 5920 +464 ========================================== + Hits 3631 3999 +368 - Misses 1825 1921 +96 ```

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