Make smoke-test generation in `fedify init` opt-in (or opt-out)

[2chanhaeng]

Summary

#990 makes fedify init unconditionally generate a smoke-test script (scripts/smokeTest.ts) together with a test task/script and, for Node.js-based package managers, a tsx dev dependency. This issue proposes turning that into an opt-in flag (working name: --smoke-test or --with-smoke-test): by default nothing extra is generated, and users who want the smoke test ask for it explicitly.

Motivation

• Less generated code for newcomers to digest. For a beginner, every auto-generated file is one more thing they feel obliged to read and understand before they trust their project. A scaffold that stays minimal by default is less stressful to approach; the smoke test is a convenience, not something the app needs to run.
• Experienced users will find the flag themselves. Developers who want a smoke test are exactly the ones who skim fedify init --help and pick the options they need, so an opt-in flag reaches its audience without imposing on anyone else.
• Avoids side effects on projects that did not ask for it. Some framework scaffolders ship their own testing setup (e.g. a SvelteKit project scaffolded with Vitest already claims the test script), and the smoke test pulls in an extra dev dependency (tsx) on Node.js-based package managers. Making generation explicit sidesteps both concerns.
• The CLI already has precedent for behavior-toggling flags: --skip-install, --allow-non-empty, and --dry-run in packages/init/src/command.ts.

Proposed behavior

• fedify init --smoke-test generates what Add a smoke test to generated fedify init apps #990 currently generates unconditionally:
  • scripts/smokeTest.ts,
  • the test task (deno.json) / test script (package.json),
  • the tsx dev dependency where the smoke test needs it.
• Without the flag, none of the above is generated.
• No new interactive prompt: the flag is CLI-only, mirroring how --skip-install works today.

Acceptable alternative: opt-out

The discussion in #898 leaned toward giving every generated project a working test task out of the box, which an opt-in default walks back. If maintainers prefer to keep that default, an opt-out flag (--no-smoke-test) that skips the generation is an acceptable outcome for this issue as well. The core request is that smoke-test generation becomes controllable from the CLI; whether the default is on or off is open to maintainer preference.