Add JWL equation of state and detonation modeling for the five-equation model

[fahnab666]

Summary

The goal is unchanged: Jones-Wilkins-Lee (JWL) detonation products in the five-equation Allaire model (model_eqns = 2), selectable per fluid (fluid_pp(i)%eos) and coexisting with an ideal-gas or stiffened-gas ambient, so MFC can simulate explosive products expanding into air or water. This was previously raised in #1384; a monolithic implementation was submitted as #1586 and closed in favor of an incremental equation-of-state architecture. This issue now tracks that incremental ladder: a central thermodynamics interface first, then explicit EOS selection, then a generic Mie-Gruneisen backend, and only then JWL as a particular Mie-Gruneisen reference curve with user-supplied parameters.

Roadmap

Step	Scope	Status
PR 1	Central thermodynamics interface; all solver paths query one module, results bit-identical	#1663 (in review)
PR 2	Explicit per-fluid EOS selector with a stable enumeration; unsupported choices rejected at validation	#1664 (in review)
PR 3	Generic Mie-Gruneisen core: reference-curve provider plus curve-agnostic assembler, manufactured verification	#1665 (in review)
PR 4	Nonreactive JWL as a Mie-Gruneisen reference curve, products-ambient mixture closure, synthetic cases only	planned
PR 5	External material-file mechanism with provenance; no named-explosive catalog in the repository	planned
PR 6 to 10	Separation of reaction integration from chemistry, Pyrometheus hardening, generic progress-variable reactions, reactant-product coupling, specific burn models	planned

Target capability (from the original proposal)

• JWL pressure law for pure products:

$$p = A\left(1-\frac{\omega}{R_1V}\right)e^{-R_1V} + B\left(1-\frac{\omega}{R_2V}\right)e^{-R_2V} + \omega\rho e, \qquad V=\frac{\rho_0}{\rho}.$$

• A composition-weighted mixture closure between JWL products and the ambient, with a closed-form pressure-energy inverse and analytic sound speed, degenerating exactly to the pure laws at the mixture endpoints.
• Optional reaction sources, off by default: kinematic program burn, products-air afterburn, and JWL++ (Souers 2000) reactive burn.
• Coupling with immersed boundaries and Euler-Lagrange bubbles.
• Validation: exact Riemann star states, resolved ZND structure against the analytic Hugoniot/Rayleigh/CJ construction, Sedov-Taylor blast scaling, far-field TNT overpressure against Kinney-Graham.

References

• Arienti, M., Morano, E., Shepherd, J.E., Shock and detonation modeling with the Mie-Gruneisen equation of state, GALCIT Report FM99-8 (2004).
• Souers, P.C. et al., JWL++: A Simple Reactive Flow Code Package for Detonation, Propellants, Explosives, Pyrotechnics 25 (2000).
• Garno, J.M. et al., Phys. Rev. Fluids 5, 123201 (2020), reactant energy offset for resolved ZND structure.

Related: #1384, #1586