RuelasF/GRIAL ? reverse-engineered prompt

Build me this GRIAL codebase, a Fortran hydro simulation for general relativistic fluid flow around a fixed analytic spacetime. I want it to compile into a single grial executable, read one parameter file, run a simulation, and write the usual outputs like checkpoints, VTK files, and basic diagnostics. Please make sure it supports the existing user workflows from the README, including a quick parameter check mode, OpenMP on the CPU, and the test suite with make test.

The main goal is a solid baseline GRHD solver with the problem presets already described in the repo, especially the Fishbone Moncrief accretion torus and the jet setup. Keep the code stable and easy to run from the command line, with clear errors when the parameter file is wrong. If anything is unclear from the code or docs, look up current docs online if you need to.

Also make sure the build is clean from the root with make -j, and that the outputs land in sensible folders by problem and method.