Fix world age issue in BNG parameter parsing

[ChrisRackauckas]

Summary

Fixed UndefVarError: kp1 not defined in BNG Birth-Death Test by resolving a world age issue when accessing parameter variables from a dynamically created module.

Changes Made

• Modified exprs_to_defs() function signature to accept parameters as a direct argument
• Replaced getproperty(opmod, psym) with direct parameter lookup using a mapping dictionary
• Updated the function call in loadrxnetwork() to pass the parameters argument

Root Cause

The error occurred because the code tried to access parameter variables from a dynamically created module using getproperty(opmod, psym), but there was a world age mismatch preventing access to the newly defined variables in the module.

Solution

Instead of trying to retrieve parameters from the module, we now pass the already-created parameter variables directly to the function and use a simple dictionary lookup: psym_to_pvar = Dict(nameof(p) => p for p in ps).

Test Results

• ✅ BNG Birth-Death Test now passes
• ✅ All existing tests continue to pass
• ✅ Code formatted with JuliaFormatter

Test Plan

• Run specific failing test (test_nullrxs_odes.jl)
• Run full test suite to ensure no regressions
• Format code with JuliaFormatter

🤖 Generated with Claude Code