Add GitHub Actions CI (OpenModelica tests, mofmt formatting) and fix failing examples

[bmazurie]

Summary

This PR adds two GitHub Actions workflows: automatic OpenModelica tests compared with master, and automatic formatting of the Modelica code with mofmt. It also fixes the 3 models that failed with OpenModelica. On the branch, 22/22 tested models simulate, against 19/22 on master.

CI: OpenModelica tests (.github/workflows/openmodelica-tests.yml)

• What is tested: the non-partial models of the Examples and Tests packages (22 models). They are run with ModelicaTests in the openmodelica/openmodelica:v1.26.7-ompython image, with MSL 3.2.3.
• Comparison with a reference version: the same models are run on the reference and compared with the branch.
  • Reference for a pull request: the target branch.
  • Reference for a push to master: the previous commit.
  • Configurations: .test/config_new_openmodelica.json (tested version) and .test/config_ref_openmodelica.json (reference, checked out in ref/TAeZoSysPro).
• Report: .test/report.py writes the run summary.
  • The results table of the ModelicaTests HTML report for the tested version.
  • For each model, its status on both versions (✅ fixed, ❌ regression, ⚠️ still failing).
  • For models simulated in both, the relative differences of the final values of all variables, computed as in ModelicaTests. The 10 largest are listed for each changed model.
• Artifacts, kept 7 days: the ModelicaTests CSV/HTML reports and the OpenModelica check, build and simulation logs of each model.
• Failure policy: a failing model does not fail the workflow; it is only reported. The workflow fails on infrastructure errors only.
• Triggers: push to master, pull requests to master, manual run.

Required setting: ModelicaTests is private. Add a repository secret MODELICATESTS_TOKEN, a GitLab token with read_repository access to ModelicaTests. For the same reason, pull requests from forks, including this one, cannot access the secret: the test job is skipped instead of failing. The results of this branch can be seen in the fork's runs: https://github.com/bmazurie/TAeZoSysPro/actions

CI: mofmt formatting (.github/workflows/mofmt.yml)

• On pull requests from a branch of this repository, mofmt 0.6.0 formats the .mo files and github-actions[bot] pushes a style: format Modelica code with mofmt commit to the branch.
• On pull requests from forks and pushes to master, nothing is pushed; the job fails if some files are not formatted.
• A UTF-8 BOM, which makes mofmt panic, is stripped before formatting.

Library changes

• Whole library reformatted with mofmt, in the bot commits f80a1f5, 665251e and 70983cd. This touches 170 .mo files, without semantic change: the test results of all unchanged models are identical. To review the rest, look at the other commits one by one.
• UTF-8 BOM removed from 4 files (MoistAir.mo, GasNode_two_phases.mo, Conduction.mo, FanVentilation.mo).
• FluidDynamics.Examples.Pressure_coocker:
  • SimpleOpening, removed in 53fb7ef, is replaced by Opening.
  • MoistAir is redeclared: GasNode_two_phases needs a condensable medium, and the default medium MyMedia has been SimpleAir since da9e7c9.
• PDE.Examples.DiffusionGaussian and PDE.Examples.BoundaryStepDiffusion: add the missing ; after the last equation. The experiment annotation was attached to that equation and ignored. As a result, DiffusionGaussian started at t = 0 and divided by zero, and BoundaryStepDiffusion stopped at 1 s instead of 300 s.
• HeatTransfer.Functions.ExchangerEffectiveness.Tests.test_counterCurrent: the Cr ramp now stops at 0.99. counterCurrent evaluates its general formula, which is 0/0 at Cr = 1, even where regStep only uses the Cr = 1 limit.

Test results (branch vs master)

	master	branch
Models simulated	19/22	22/22

• Fixed: Pressure_coocker, test_counterCurrent, DiffusionGaussian.
• Results changed: BoundaryStepDiffusion, which now runs until 300 s.
• The 18 other models are unchanged: final values are identical within a relative tolerance of 1e-4.

Known limitations and follow-ups

• The formatting commit pushed by the bot does not trigger the tests again (GitHub does not run workflows on commits pushed with GITHUB_TOKEN).
• counterCurrent still divides by zero at Cr = 1. Components that use it (HeatExchanger, AnalyticExchanger, DiscreteExchanger) would fail if both heat capacity rates became equal. Not changed here.
• Inverse.NTU_coCurrent has an inverse annotation pointing to counterCurrent instead of coCurrent, probably a copy-paste error. Not changed here.
• ModelicaTests issues to report upstream:
  • Its git url feature clones into REPO_<lib>_<n>, which fails when package.mo is at the repository root, as here.
  • compare_res crashes when a result file has no variable.
  • The comparison CSV is written without model names.
• A .git-blame-ignore-revs file listing the mofmt commits could be added, so that git blame skips the reformatting.