[v2] Add PowerShell (pwsh) shell completions

[mynameistito]

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Request

Please add PowerShell (pwsh) completion support to the v2 executor CLI. PowerShell users currently cannot generate native completions: executor --help lists only bash, zsh, fish, and sh for --completions.

Current behavior

On Windows, running:

executor --completions pwsh

is not supported by the listed choices. Also, requesting Bash completions for a nested command currently appears to emit only the marker, with no completion entries:

executor apps --completions bash

Output:

###-begin-executor-completions-###

Expected behavior

• pwsh is an accepted value for --completions and prints a PowerShell-native completion script suitable for registering with Register-ArgumentCompleter.
• Generated completions cover the v2 CLI's subcommands and flags, including nested commands such as apps.

Environment

• Windows / PowerShell (pwsh)
• Executor v2 CLI

I searched the existing issues for PowerShell completion support and did not find a duplicate.