v0.4.0

• install.ps1: the installer for Windows 10 and 11
  (irm .../install.ps1 | iex), with the same runtime choice, environment
  variables and kept skills directory as install.sh. It runs under Windows
  PowerShell 5.1 and PowerShell 7. The checkout goes to
  %LOCALAPPDATA%\house-rules.
• install.sh and install.ps1: a run in the same second as the previous one
  keeps its own backup of the skills directory instead of nesting it inside the
  earlier backup.
• .gitattributes checks text files out with LF line endings on every
  platform.
• stock-ui-audit: findings name files with forward slashes on Windows too.
• CI also runs the tests on Windows.