[rhorvath02]

Add mirrored fixture coverage, component/physics regressions, parameter/import checks, diagram-routing checks and fixture profiling for the migrated Modelica library. Preserve the numerical baseline inventory rather than regenerating it.

Fix the mounted-transmission regression to use a unique output prefix for each simulation, avoiding the filename/GUID collision in repeated OMC builds.

Validation: 1,059 tests collect; 613 focused structural/diagram/documentation/coverage checks pass; the mounted-transmission regression passes; 132 mirrored fixtures validate; Ruff passes. These are fresh checks on the isolated stack, not a full numerical-suite pass.

Only test-harness Python is included. Tools/, native/FMU exporters/runners and SS/GGV analysis are excluded, along with tests requiring that tooling. Actual OMEdit acceptance remains outstanding.

Stack (merge bottom-up):

1. [Modelica] Modernize vehicle assemblies and mirrored fixtures #33
2. [Tests] Add regression, coverage and diagram checks #34 — this PR
3. [Release] Wire release gates and document the Modelica migration #35

[rhorvath02]

Superseded by the smaller subsystem stack starting at #37. Test-library and validation layers are #49–#53; full stack index: #54.