One command to drive all

A short shell script called `pkg` provides a unified interface for common package manager operations across multiple operating systems including Ubuntu, macOS (Homebrew), Arch Linux, OpenBSD, Solus, Void Linux, and PureOS. Using single-letter mnemonic flags (i, r, s, u, l, c), it abstracts away the differences between apt, brew, yay, pkg_add, eopkg, and xbps. A bonus tip covers using it as an Emacs Eshell alias with argument passing.