Polish Windows install guide

[TheNorthStarYang]

Goal

Describe and improve this part of the AhaKey Desktop baseline so that new users and contributors can follow it more easily.

Scope

• keep changes focused
• avoid unrelated refactors
• prefer documentation clarity over complexity

Where to edit

• repository: desktop
• relevant path: docs/install-windows.md

Notes

This issue is part of the early community onboarding / baseline cleanup.

Contributors are welcome.