Backend:
- Add POST /api/optimization/studies/{study_id}/nx/run-baseline endpoint
- Creates trial_baseline folder in 2_iterations/
- Copies all model files and runs NXSolver
- Returns paths to result files (.op2, .f06, .bdf) for extractor testing
Frontend:
- Add 'Run Baseline Simulation' button to IntrospectionPanel
- Show progress spinner during simulation
- Display result files when complete (OP2, F06, BDF)
- Show error messages if simulation fails
This enables:
- Testing custom extractors against real FEA results
- Validating the simulation pipeline before optimization
- Inspecting boundary conditions and loads