Add Lao beta_p/li profile adjustment for VCs

[nicamo]

Summary

• add a static Lao85 fitter that targets Ip, beta_p and li using two alpha and two beta coefficients
• add a VC profile_adjuster route and a helper for VCs at fixed beta_p/li
• update example09 with an executed fixed beta_p/li VC workflow and silence the stale psi_func refresh notice
• add focused regression tests for the Lao fitter, profile state copying, and VC profile-adjuster plumbing

Tests

• python -m pytest freegsnke/tests/test_jtor_update.py freegsnke/tests/test_virtual_circuits.py -q
• python -m black --check freegsnke/equilibrium_update.py freegsnke/jtor_update.py freegsnke/virtual_circuits.py freegsnke/tests/test_jtor_update.py freegsnke/tests/test_virtual_circuits.py
• executed examples/example09 - virtual_circuits_MASTU.ipynb in place with nbconvert
• validated the executed notebook with nbformat