urfave/cli ? reverse-engineered prompt

Build me a Go library for making command line apps that feels simple and easy to use, but still powerful. I want commands and subcommands, alias support, prefix matching, and a helpful built in help screen that is forgiving and easy to read.

It should support shell completion for bash, zsh, fish, and powershell, and let me define flags for basic values, slices, durations, times, and other common types. I also want compound short flags like using abc instead of typing each one separately.

Make it work without any third party dependencies if possible, just the Go standard library. It should also support reading values from environment variables, plain text files, and structured config files. If it makes sense, include support for generating docs in man pages and Markdown.

Please make it feel polished, with good error messages, sensible defaults, and a clean API that a Go developer could use to build real CLI tools quickly.