Terminal users often wire grut into their shell, but today they have to remember every command and flag. Add a completion subcommand that prints scripts for bash, zsh, fish, and PowerShell using Cobra's built-in generators.
Acceptance criteria:
grut completion <shell> supports bash, zsh, fish, and powershell.- Unsupported shells return a clear error.
- The command is registered in root help and covered by tests.
Terminal users often wire grut into their shell, but today they have to remember every command and flag. Add a completion subcommand that prints scripts for bash, zsh, fish, and PowerShell using Cobra's built-in generators.
Acceptance criteria:
grut completion <shell>supports bash, zsh, fish, and powershell.