Add/docs windows build commands

[bhaskarvilles]

Windows build section modified from 5 sparse bullets → a full, actionable guide:

• Explains why Git Bash is needed (POSIX utilities)
• Exact winget install commands for every tool (Git, jq, 7-Zip, Python 3.11, Rustup)
• Node.js section explains nvm-windows for version management + the "Automatically install native tools" checkbox tip
• WiX Toolset is now correctly marked as optional (only for -p installer packaging)
• New PATH verification block — a quick checklist to run in Git Bash to confirm everything is set up
• The Build section now clearly labels Git Bash as recommended over PowerShell, with a note for WSL2 users

[daiyam]

Thanks