Update installation instructions

[mih]

Recent work on packaging git-annex for PyPi has enabled new deployment approaches. IMHO things become significantly simpler, and that should be reflected in the installation instructions in the handbook.

This issue collects information on the current "optimum" deployment, with a focus on user-based (non-admin) scenarious.

[mih]

Windows

Starting point is a system with neither Git, nor Python installed.

Note, git-annex can be deployed without a prior Git installation -- but it would'nt be functional, hence we start with Git.

Git

Install Git (current 2.49.0) from https://git-scm.com/downloads/win via the standalone installer. Use default installation location and options. The handbook recommends a few
different option selections. These have not been reinvestigated, and likely should stay in-place.

Git-annex

git-annex is deployed via uv, which is installed first:

powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"

afterward git-annex can be deployed

uv tool install git-annex

later, git-annex can also be upgraded in this fashion

uv tool update git-annex

This gives a functional installation, with no explicit Python installation step. It can be verified via git annex test (about 2-3min runtime).

DataLad

DataLad is installed in the same fashion as git-annex. Also installed as a tool (auto-inclusion into the default PATH, but into its own dedicated environment. At present, the datalad package does not include a dependency on git-annex, hence it needs to be pulled manually. However, even with such a dependency it could make sense to make this step explicit, and raise user-awareness that git-annex is also a user-facing tool for them.

DataLad can be installed in a number of different configurations, using a rather clear syntax. All the following commands are possible (individual) alternatives, but can also be run successively, yielding a single datalad environment installation:

uv tool install datalad
uv tool install datalad --with datalad-next
uv tool install datalad --with datalad-next --with psutil

Followed by any necessary initial configuration, such as

git config --global --add datalad.extensions.load next

[adswa]

Thanks! I have updated the windows installation instructions with most of these suggestions.

I think we should make a conscious decision about datalad-next, though. I do not mind adding it, but I would argue we need to recommend it on every platform, not only Windows. If we do this, the installation instructions would then need to explain a bit about datalad extensions and also what makes datalad-next special.