docs: add Windows setup guide for new contributors

Author: aman-dev-maker

WINDOWS_SETUP.md

@@ -0,0 +1,88 @@
+# Windows Setup Guide
+
+To get setup for development on Windows, see 
+[this video if you prefer VS Code](https://youtu.be/zddl3n1DCFM), 
+or [this older video if you prefer PyCharm](https://youtu.be/QniQi-Hoo9A), 
+and the instructions below.
+
+## 1. Fork and clone this repo
+
+Go to https://github.com/malariagen/malariagen-data-python 
+and click the Fork button (top right corner).
+
+Then in PowerShell run:
+```bash
+git clone https://github.com/[username]/malariagen-data-python.git
+cd malariagen-data-python
+```
+
+## 2. Install Python
+
+Download and install Python 3.10 from:
+https://www.python.org/downloads/windows/
+
+> ⚠️ Important: During installation, check the box 
+> "Add Python to PATH" before clicking Install.
+
+Verify it worked:
+```bash
+python --version
+```
+
+## 3. Install pipx and poetry
+```bash
+python -m pip install --user pipx
+python -m pipx ensurepath
+pipx install poetry
+```
+
+> ⚠️ After running ensurepath, close and reopen 
+> PowerShell before continuing.
+
+## 4. Create and activate development environment
+```bash
+poetry install
+poetry shell
+```
+
+## 5. Install pre-commit hooks
+```bash
+pipx install pre-commit
+pre-commit install
+```
+
+## 6. Add upstream remote and get latest code
+```bash
+git remote add upstream https://github.com/malariagen/malariagen-data-python
+git pull upstream master
+```
+
+> ℹ️ Note: On Windows the default branch is called 
+> master not main.
+
+## 7. Verify everything works
+```bash
+python -c "import malariagen_data; print('Setup successful!')"
+```
+
+## Common Issues on Windows
+
+**poetry not found after install**  
+Close and reopen PowerShell, then try again.
+
+**git not recognized**  
+Install Git from https://git-scm.com/download/win 
+and restart PowerShell.
+
+**python not recognized**  
+Reinstall Python and make sure to check 
+"Add Python to PATH" during installation.
+
+**fatal: not a git repository**  
+Make sure you are inside the malariagen-data-python 
+folder before running any git commands.
+Use: cd malariagen-data-python
+
+**error: pathspec main did not match**  
+On Windows use master instead of main.
+Run: git checkout master