Fix compartment removal in reaction rates for sbml2bngl

[akutuva21]

Corrected a bug in SBML2BNGL.analyzeReactionRate where compartment sizes were incorrectly removed from reaction rate equations. The original code attempted to parse the numerator and denominator using as_numer_denom(), which failed on multi-term mathematical expressions (e.g., reversible reactions with minus signs) because subtraction prevents the extraction of a clean multiplicative denominator.

By substituting the compartment symbol with 1 using sym.subs(comp, 1), we cleanly remove its multiplicative effect regardless of where it appears in the mathematical expression. This robust symbolic approach accurately unrolls compartment size scaling from the rate laws.

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PR created automatically by Jules for task 12651291564637042192 started by @akutuva21

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