Use latest PlatyPS for module help

[adamdriscoll]

The VS Code extension modules were missing local Get-Help content, and the build still used the legacy PlatyPS package. This updates help generation to the supported Microsoft.PowerShell.PlatyPS 1.0.1 module and checks in generated command help for both packaged modules.

Summary:

• Adds Markdown and external MAML help for PowerShellProTools.VSCode commands.
• Expands PowerShellProTools command help beyond Merge-Script.
• Wires the cmdlet and VS Code extension builds to generate help with Microsoft.PowerShell.PlatyPS 1.0.1.
• Updates CI/publish setup docs to install the supported PlatyPS package.

Validation:

• Imported and validated 31 Markdown help files with Microsoft.PowerShell.PlatyPS.
• Verified Get-Help loads generated help for ConvertTo-WinForm and Show-VSCodeMessage.
• Built HostInjection\PowerShellProTools.Common.csproj and PowerShellToolsPro.Cmdlets\PowerShellToolsPro.Cmdlets.csproj in Release.

Closes #132