The Jupyter notebook is on its way out, users are encouraged to transition to JupyterLab.

• Make JupyterLab an optional package #26059/Add optional packages jupyterlab, jupyterlab_widgets to support interacts in JupyterLab #30246 Make JupyterLab an optional package, support interacts in JupyterLab
• Upgrade jupyterlab to 3.3.x, add "sage -n nbclassic" and "sage -n retrolab" #32069 Upgrade jupyterlab to 3.0.x
• Add package pythreejs 2.3.0 #32070 Add package pythreejs 2.3.0
• System package information, spkg-configure for Jupyter "notebook" package, "rst2ipynb", and dependencies #30124 System package information, spkg-configure for Jupyter "notebook" package, "rst2ipynb", and dependencies
• Meta-ticket: Improve live documentation in the Jupyter notebook #20893 Improve live documentation in the Jupyter notebook
• Repackage Sage's cropped threejs as a pip-installable package (nbextension) jupyter-threejs-sage #30123 Repackage Sage's cropped threejs as a pip-installable package (nbextension) jupyter-threejs-minimal
• Make jupyterlab a standard package, update notebook to 7.x #24904 Make jupyterlab a standard package

CC: @paulmasson @jcamp0x2a @slel @zerline @fchapoton

Component: notebook

Issue created by migration from https://trac.sagemath.org/ticket/30399