fix(create-indiekit): handle command-line arguments

[rmdes]

Fixes #908.

create-indiekit never read process.argv, so --help and --version fell through to the setup questions, and an unrecognised option became the name of the scaffolded directory — base-create takes process.argv[2] verbatim.

What this changes

• lib/cli.js (new) parses arguments with parseArgs from node:util. --help/--version print and exit 0; an unrecognised option is named and exits 1.
• A missing directory is reported before any question is asked. base-create already requires one, but only checks after the last answer, so those answers were thrown away.
• bin/create.js checks for an interactive terminal before prompting. Without one, prompts never settles and Node reported an unsettled top-level await; it now says what's wrong and exits 1.
• index.js passes onCancel to prompts. Cancelling resolved with whatever had been answered so far, so a cancelled run carried on and scaffolded with empty answers. It now throws, and bin/create.js turns that into a clean exit 1.

Notes on the approach

Parsed non-strictly, so an unrecognised option is reported by name rather than throwing. Under strict: true, parseArgs throws on anything unknown, which would turn a currently-harmless stray option into a crash.

I used parseArgs rather than commander to avoid adding a dependency — the package already imports from node:util, and this needs two booleans and one positional. packages/indiekit uses commander for its CLI, so say the word if you'd rather the two binaries matched and I'll switch.

Cancellation is signalled with an error.code of ERR_SETUP_CANCELLED rather than calling process.exit() in index.js, since unicorn/no-process-exit restricts that to the binary.

Verification

packages/create-indiekit unit tests: 23 pass, 0 fail (9 new, in test/unit/cli.js). eslint and prettier clean.

$ node bin/create.js --help          # usage, exit 0
$ node bin/create.js --version       # 1.0.0-beta.29, exit 0
$ node bin/create.js --foo           # Unknown option: --foo, exit 1
$ node bin/create.js                 # Provide a directory. exit 1
$ node bin/create.js myproject       # (no TTY) This command needs an interactive terminal. exit 1

No directory named --help is created in any of those.

Not addressed here

Two inconsistencies noted in #908 that felt out of scope for this change: engines.node is >=24.17 while the runtime guard in bin/create.js only rejects Node < 20, and docs/get-started.md documents the directory as optional though base-create requires it. Happy to fold either in.