Command-line argument parsing.

Supports flags (--verbose), options (--output file), short aliases (-v), and positional arguments. Automatically generates help text.

Example

{ ArgParser } :: import "std/cli/arg_parser";

parser := ArgParser.new(`myapp`, `A sample CLI tool`);
parser.flag(`verbose`, `v`, `Enable verbose output`);
parser.option(`output`, `o`, `Output file`, `out.txt`);
args := parser.parse();