v0.5.2 — Retain rejected Safe PINN evaluations

The Safe PINN demo now saves its completed evaluation before checking held-out improvement and terminal accuracy. If a final check rejects the result, result.mat, metrics.json and training.csv remain available, and the console identifies their directory. The original assertion still throws.

• Added a real zero-update demo regression; all 104 local MATLAB tests passed.
• GitHub Actions passed repository checks and all 104 MATLAB tests on Ubuntu 24.04 with R2025b Update 6.
• A separate one-update success comparison preserved network parameters and numerical result fields, excluding timing. This uses its own curriculum and does not reproduce the 5,000-update experiment.
• The demo, its test and the test-runner description are the only changed MATLAB files. Network formulas, default settings, acceptance thresholds and historical experiments are unchanged.
• Original v0.5.1 validation records are archived, and the mean-field comparison remains tied to its tested source.

This patch preserves completed evaluations. Recovery from nonfinite losses during training or earlier evaluation errors is separate work. Full neural training was not rerun.

Validation and source identity · Inspecting a saved evaluation