Chocolately Shell

I believe there is some discussion (at time of writing) about what to do for command aliases. They exist but are depreciated and the recommended method is "choco _command_". I think a choco "shell" would be an appropriate compromise.

Executing "choco" without a command would open a "shell" instead of displaying documentation. With a command it would use the current behavior. Users could then execute commands without the choco prefix and it would not break current functionality.

This could also potentially be used to expand choco's capabilities and usage in the future.

Start by reviewing Chocolatey's current behavior when invoked without a command and the existing command-alias discussion. Define the proposed shell's command-loop behavior and compatibility boundaries, then confirm that command invocation still works as before and that the no-command path has clear documentation and tests.

Written by the indexing model from the issue text.