Tutorial notebooks

Executed notebooks live in tutorials/ and are re-run by CI, so their outputs match the current release.

• 01 — From atmosphere to a corrected PSF: a layered atmosphere drives a minimal modal AO loop (Zernike "DM", one-frame-delay integrator); the closed-loop residual is compared with Noll's fitting-error floor and the long-exposure Strehl with the Maréchal approximation.

Run them locally with pip install "pyturb[plot]" jupyter.