Add NeqSim FEM workflows with FEniCSx, Gmsh, scikit-fem and PyVista

[EvenSol]

Summary

Adds two connected NeqSim-Colab FEM tutorials:

1. notebooks/fluidflow/neqsim_fenicsx_fem_pipeline.ipynb

   • source-builds current NeqSim Java master and records commit/JAR provenance
   • calculates fluid transport properties and 1D pipeline thermal boundary conditions
   • resolves a local degraded-insulation temperature field with axisymmetric FEniCSx
   • validates against cylindrical thermal resistance and mesh refinement
   • compares NeqSim SurfCooldownAnalyzer with a local FEM cooldown/hydrate cold-spot calculation
   • demonstrates axisymmetric thermo-elastic stress under internal/external pressure and thermal gradients

2. notebooks/fluidflow/finite_element_methods_oil_gas_neqsim.ipynb

   • establishes the reusable NeqSim → Gmsh → scikit-fem/FEniCSx → PyVista stack
   • demonstrates lightweight radial pipe heat transfer with scikit-fem
   • creates a damaged-insulation geometry and physical groups in Gmsh and transfers them directly to DOLFINx
   • visualizes FEM fields with PyVista
   • uses NeqSim multicomponent CO2 diffusivity in a porous-rock diffusion example
   • demonstrates FEniCSx wellbore-to-formation heat conduction

A temporary PR-only workflow executes both notebooks in the official dolfinx/lab:stable container, runs the repository notebook integrity checks, updates the catalog and maintenance ledger, commits retained outputs, and removes itself before the PR is marked ready.