allow checkpoint-free analytic wf evaluation

[AllanChain]

Parameter-free wavefunctions, like the Laughlin wavefunction in fractional quantum Hall, can be evaluated from a fresh state without a training checkpoint. Rejecting them in VMC makes that workflow boundary explicit.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 88.23529% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.51%. Comparing base (6dee554) to head (df69d86).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/jaqmc/workflow/evaluation.py	86.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #74      +/-   ##
==========================================
+ Coverage   89.47%   89.51%   +0.04%     
==========================================
  Files         163      163              
  Lines        8775     8784       +9     
  Branches      933      936       +3     
==========================================
+ Hits         7851     7863      +12     
+ Misses        602      601       -1     
+ Partials      322      320       -2     

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