[DOC] Add WSL setup guide and setup script for Windows contributors

[direkkakkar319-ops]

Reference Issues/PRs

No existing issue — proactive documentation improvement for Windows contributors.

What does this implement/fix? Explain your changes.

skbase currently has no documentation for Windows users who want to
contribute using WSL (Windows Subsystem for Linux). This PR adds both
the documentation page and the automated setup script.

Two files added:

1. docs/source/contribute/development/wsl_setup.rst

   • Installing WSL and Ubuntu on Windows
   • Cloning the repository inside WSL filesystem
   • Automated setup via the shell script
   • Manual virtual environment activation
   • Verifying installation with pytest

2. scripts/setup_wsl.sh

   • Updates apt package lists
   • Installs python3-venv and python3-pip
   • Creates .venv_wsl virtual environment (skips if already exists)
   • Activates the environment
   • Upgrades pip
   • Installs skbase in editable mode with [dev,test] dependencies

Does your contribution introduce a new dependency? If yes, which one?

No new dependencies introduced. Documentation and shell script only.

What should a reviewer concentrate their feedback on?

• Is docs/source/contribute/development/ the right location for
  the RST page?
• Does the shell script cover all necessary setup steps for Ubuntu WSL?
• Should a WSL2 vs WSL1 recommendation note be added to the docs?
• Is .venv_wsl the right name for the virtual environment or should
  it follow an existing convention in the project?

Any other comments?

This guide is aimed at Windows contributors who are new to open source
and may not know how to set up a Linux-like development environment.
Since skbase has no Windows development guide currently, this lowers
the barrier to entry for a large group of potential contributors.

The shell script uses set -e to exit immediately on any error,
and safely skips virtual environment creation if .venv_wsl already
exists to make it safe to re-run.

Tested on Ubuntu WSL — all tests pass after running scripts/setup_wsl.sh.
Screenshot attached below:

PR checklist

For all contributions

• I've reviewed the project documentation on contributing
• I've added myself to the list of contributors.
• The PR title starts with either [ENH], [CI/CD], [MNT], [DOC], or [BUG] indicating whether
  the PR topic is related to enhancement, CI/CD, maintenance, documentation, or a bug.

For code contributions

• Unit tests have been added covering code functionality
• Appropriate docstrings have been added (see documentation standards)
• New public functionality has been added to the API Reference

[direkkakkar319-ops]

Hi, @fkiraly I have raised this PR to add a WSL setup guide for Windows contributors since skbase currently has no Windows development docs.

Includes both the RST documentation page and the scripts/setup_wsl.sh automation script.