feat: Add additional constraint options for enforceEquilibrium

[frankfeifan]

This PR adds more constraint options for each primary species in the enforceEquilibrium solve in addition to the original AggregateConcentration option. Available constraint options include AggregateConcentration, pX, and ChargeBalance.

Species changes are:

• Introduced a PrimarySpeciesConstraintType enum (AggregateConcentration, pX, ChargeBalance, and a placeholder MineralEquilibrium) so each row of the equilibrium solve can be closed by a different constraint.

• Generalized enforceEquilibrium_Aggregate into enforceEquilibrium_PrimaryConcentrations, which takes a per-species constraint type and value array and now also returns the converged aggregate (total) concentrations.

• Implemented the new residual/Jacobian rows in computeResidualAndJacobianPrimaryConcentrations — a row with pX constraint type enforces ln(a_i) + pX·ln(10) = 0, while the row with ChargeBalance type ensures charge electroneutrality over the mobile aggregate concentrations.

• Added EQ3NR-verified tests for the new constraints: a pH-constrained carbonate case that recovers the withheld total H⁺ (3.76e-1) from the same carbonate.3o reference run, and a charge-balance-on-Cl⁻ case that recovers the analytically implied Cl⁻ aggregate.

[codecov]

Codecov Report

❌ Patch coverage is 99.87995% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 99.92%. Comparing base (7423e3e) to head (be4f3b8).

Files with missing lines	Patch %	Lines
...EquilibriumReactionsPrimaryConcentrations_impl.hpp	98.71%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##              main      #25      +/-   ##
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- Coverage   100.00%   99.92%   -0.08%     
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  Files           25       35      +10     
  Lines          830     1387     +557     
===========================================
+ Hits           830     1386     +556     
- Misses           0        1       +1     

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