3.3.0

• BNS Z-factor / critical-property coupling: When either zmethod or cmethod is BNS, both are now forced to BNS for thermodynamic consistency with a UserWarning naming the overruled counterpart. h2 > 0 continues to auto-select BNS silently. Non-BNS methods (e.g. DAK + SUT) remain freely mixable. Implemented via a single _resolve_methods helper applied at all gas public entry points plus GasPVT.__init__.

• User-supplied tc / pc honored across every method (including BNS). Semantics:

  • SUT / PMC: supplied values replace the mixture pseudo-critical Tc/Pc.
  • BNS: supplied values replace only the inert-free hydrocarbon pseudo-component Tc/Pc. Inert Tc/Pc (CO2, H2S, N2, H2) remain at BNS internal constants, and the BNS 5-component PR-EOS mixes them with the user-supplied HC Tc/Pc.

  This is reflected in gas_tc_pc, gas_z, gas_ug, gas_cg, gas_bg, gas_den, gas_dmp, gas_ponz2p, gas_grad2sg, and GasPVT (new tc=0, pc=0 kwargs on the class constructor).

• Rust parity for user Tc/Pc: The Rust batch paths (dak_zfactor_batch, hy_zfactor_batch, bns_zfactor_batch, gas_ug_lbc/gas_ug_lbc_batch, gas_dmp_rust, gas_ponz2p_rust) now accept optional tc_user / pc_user parameters and apply the same override semantics as Python. Removes the previous Python fallback for BNS+user-Tc/Pc; Rust path is now always exercised.

• 716 validation tests (up from 701 in 3.2.0). New coverage for BNS coupling warnings, GasPVT user Tc/Pc, and Rust-vs-Python parity for user Tc/Pc.