feat(windows): ✨ add native installation and setup support - #8

Why

The Go binary already builds for Windows, but the repository had no native Windows installation path.

The existing install.sh advertised Windows support but relied on Unix-only behavior such as mv, chmod, and symlinks, which could fail under Git Bash/MSYS.

What changed

• Added a native PowerShell installer for Windows.
• Added support for Windows amd64 and arm64 release archives.
• Installed playconsole-cli.exe and a gpc.exe alias in the user-local programs directory.
• Added the install directory to the user PATH.
• Fixed the Git Bash installer path for Windows, including .exe handling and alias creation without symlinks.
• Added Google Cloud CLI installation through winget in setup --auto.
• Documented Windows installation and development workflows.
• Added a Windows build and test job to CI.
• Corrected authentication profile examples in the command documentation.

Validation

Tested on Windows 11:

• PowerShell installer tested end to end against release 0.5.15.
• playconsole-cli.exe version and gpc.exe version verified.
• Native Windows build passed.
• GOOS=windows GOARCH=amd64 build passed.
• internal/api and internal/cli tests passed.

Compatibility

No API changes were introduced. Linux and macOS behavior remains unchanged.