add small program to parallelize snakemake across nodes on NERSC

[gipert]

• signal handling
• docs
• fix circular dependency problem

[codecov]

Codecov Report

❌ Patch coverage is 4.34783% with 66 lines in your changes missing coverage. Please review.
✅ Project coverage is 61.07%. Comparing base (8c9da09) to head (98aa997).
⚠️ Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
workflow/src/legendsimflow/cli.py	0.00%	65 Missing ⚠️
workflow/src/legendsimflow/utils.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #62      +/-   ##
==========================================
- Coverage   64.56%   61.07%   -3.50%     
==========================================
  Files          18       19       +1     
  Lines        1143     1210      +67     
==========================================
+ Hits          738      739       +1     
- Misses        405      471      +66     

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