Add `--skip-install` (parity with `prisma orm init --skip-install`): no way to scaffold files without installing dependencies

[ankur-arch]

Summary

create-prisma has no way to generate a project without installing dependencies. prisma orm init has --skip-install; create-prisma rejects it:

$ npm create prisma@latest -- nest-ref --template nest --provider postgres --yes --skip-install

ERROR
  Unrecognized flag: --skip-install in command create-prisma

(create-prisma@0.13.1, npm 11.6.2, Node 24.11.1, macOS.)

Why it matters

• Inspecting a template. I wanted to compare what --template nest emits against a hand-wired NestJS 12 project. That needs the files, not node_modules. A full install of the nest template pulls in @prisma/composer, alchemy, tsdown and friends, which takes minutes on a cold cache for something I was going to delete.
• Agents and CI. The CLI already advertises itself as agent-friendly (--yes, --json). Agents typically generate first and install once, after they have edited package.json (for example to add @nestjs/cli, or to pin a different @prisma/orm-postgres rc). Today that means "install, edit, install again".
• Offline / monorepo scaffolding. In a pnpm or turborepo workspace, the install has to run from the workspace root anyway; the nested install create-prisma performs is wasted and can leave a stray lockfile.
• --json implies deploy. The help text says --json "deploys unless --no-deploy", so the only non-interactive mode does more work by default, not less. A --skip-install flag is the natural counterpart.

Proposal

Add --skip-install (matching the prisma orm init flag name so the two CLIs read the same):

--skip-install    Write the project files but do not install dependencies
                  (also skips the initial `prisma contract emit`, which needs them)

Behaviour:

1. Scaffold all files exactly as today, including package.json.
2. Skip the package-manager install step and the post-install steps that need node_modules (prisma contract emit, prisma db init, skills sync).
3. Print the commands the user needs to run next, and include them in the --json result as nextActions, the same way prisma orm init does:

{
  "ok": true,
  "packagesInstalled": { "status": "skipped" },
  "contractEmitted": false,
  "nextActions": [
    { "kind": "run-command", "command": "npm install" },
    { "kind": "run-command", "command": "npx prisma contract emit" }
  ]
}

4. --skip-install with --deploy should be an error (deploy needs a build).

Alternatives

• --package-manager none: less discoverable and does not express intent.
• Generating into a temp dir and killing the process during install: what I actually did, which is not great.