POSIX-style flag conventions

Users have thirty years of muscle memory around POSIX flags. When -verbose works but --verbose does not, or when --port=3000 silently parses as --port with a positional =3000, users assume the tool is broken and stop typing. Non-standard flag syntax also breaks shell completions, wrapper scripts, and Makefile recipes that assume GNU conventions. A tool that invents its own flag grammar is a tool that will never be piped into anything.

Use a standard argument parser (commander, yargs, click, cobra, clap) and avoid writing custom flag logic in src/cli/parse-args.ts or equivalent. Short flags must be -x, long flags must be --xxx, and boolean flags must be toggles, not require explicit true/false:

program
  .option('-o, --output <path>', 'Output file')
  .option('-v, --verbose', 'Verbose output')