Use a temperature guess and report failures in iterative enthalpy inversions - #2983

Proposed Changes

Fluid models that solve for the temperature from the enthalpy iteratively currently start every solve from a fixed temperature and give the caller no way to tell that it failed. CIncIdealGasPolynomial starts at 300 K and only prints a per-point warning when it fails.

This PR adds CFluidModel::SolveTDState_h(h, Y, T_guess), which takes the starting temperature as an argument and returns whether a valid state was found. The default implementation forwards to SetTDState_h and returns true, so models that compute the temperature directly are unchanged. CIncIdealGasPolynomial inow uses the guess (falling back to the non-dimensional reference temperature) and returns failure instead of printing per-point warnings. The incompressible call sites (SetPrimVar main and fallback paths, ComputeConsistentExtrapolation, RecomputeDensity_time_n) now pass the previous temperature and handle failure explicitly.

Related Work

Replaces the SetTemperatureGuess / GetTemperatureIterationFailed pair proposed in #2713 (Cantera fluid model), which can implement SolveTDState_h instead. Also prepares for a temperature-dependent cp in FLUID_MIXTURE (see the TODO in CFluidScalar::SetTDState_h).

PR Checklist

• I am submitting my contribution to the develop branch.
• My contribution generates no new compiler warnings (try with --warnlevel=3 when using meson).
• My contribution is commented and consistent with SU2 style (https://su2code.github.io/docs_v7/Style-Guide/).
• I used the pre-commit hook to prevent dirty commits and used pre-commit run --all to format old commits.
• I have added a test case that demonstrates my contribution, if necessary.
• I have updated appropriate documentation (Tutorials, Docs Page, config_template.cpp), if necessary.