Support int64 seeds in MalariaConfig.from_params()

[edwenger]

Problem

When using create_config() with large seed values (> 2^31), the pybind11 bindings fail with:

RuntimeError: Unable to cast Python instance of type <class 'int'> to C++ type '?'

This occurs in MalariaConfig.from_params(merged) when Run_Number exceeds the int32 range.

Reproduction

from emodlib.malaria import create_config                                                                                                           
                                                                                                                                                     
 # Works (fits in int32)                                                                                                                             
 config = create_config({'Run_Number': 368693116})                                                                                                   
                                                                                                                                                     
 # Fails (exceeds int32 max of 2147483647)                                                                                                           
 config = create_config({'Run_Number': 2191622255})      

Current Workaround

In the mops-examples/emodlib-demo, we're truncating seeds to fit int32:

  params_dict = {                                                                                                                                     
      'Run_Number': int(seed) % (2**31),  # Workaround for int32 limit                                                                                
      ...                                                                                                                                             
  }          

This works but loses entropy from the full 64-bit seed space that modelops provides.

Suggested Fix

Update the C++ bindings to accept int64 for Run_Number, or add explicit type conversion/validation in the Python create_config() wrapper with a clear error message.

Context

• Discovered while running emodlib-demo on modelops k8s cluster (only on larger sweeps that didn't get lucky and always have smaller random seeds)
• The modelops framework generates random seeds as large integers (up to ~4 billion)
• See commit edwenger/mops-examples@526c3c7 for the workaround