Download aarch64-linux-musl-gcc linker step in upload-binaries job was failing for aarch64 linux target

See https://github.com/Mubashwer/git-mob/actions/runs/15495275177/job/43673822229

* feat: make --global the default behavior for setup command

Previously, the setup command required explicit --global or --local flags
and would show help when no arguments were provided. This change makes
--global the default behavior, simplifying the common use case while
maintaining backward compatibility.

Changes:
- Remove arg_required_else_help constraint from Setup command
- Make setup command default to global behavior when no flags specified
- Hide --global flag from help output while keeping it functional for
  backward compatibility
- Update command description to clarify global setup is default
- Update all documentation examples from "git mob setup --global" to
  "git mob setup"

The --global flag is still accepted but hidden from help output to avoid
confusion while ensuring existing scripts and workflows continue to work.
The --local flag remains unchanged and is only needed for repositories
that override core.hooksPath (e.g., when using husky).

This aligns with user expectations since global setup was the standard
installation method, with local setup being a specialized use case for
repositories with custom hook configurations.

* fix: correct grammar in setup command description