fix(cli): launch Windows package-manager shims through the spawn adapter

[AmanVarshney01]

Problem

The consolidated CLI delegates Composer and other commands through its own spawn adapter. That adapter used native node:child_process.spawn, which cannot execute Windows .cmd shims directly.

Reproduced

The first commit runs the real installed npm.cmd through the shipped adapter. Existing Windows CI failed with spawn EINVAL (-4071), while 951 other tests passed: https://github.com/prisma/prisma-cli/actions/runs/34236425789/job/102095202659.

Fix

Use cross-spawn at the owning adapter. Preserve argv arrays, inherited human stdio, structured diagnostic forwarding/backpressure, bounded drain, exit status, and signal forwarding. No blanket shell:true and no create-prisma workaround. Declare the runtime dependency in both published package manifests. Document the execution contract.

Verification

• Windows after fix: the same npm.cmd regression passes; all 61 CLI test files pass, 952 tests passed and 10 platform skips: https://github.com/prisma/prisma-cli/actions/runs/34237016724/job/102097241940.
• Linux CI passed: https://github.com/prisma/prisma-cli/actions/runs/34237016724/job/102097242011.
• macOS locally: all 61 CLI test files passed (960 tests, 2 platform skips).
• Repository typecheck and lint passed.
• No workflows added and no production deployment needed for the command-launch reproduction.

Scope

Fixes Windows delegated shim launch failures, not every CLI.SPAWN_FAILED, auth error, build failure, or install failure. Composer executable discovery is separate: prisma/composer#280.

Kept as draft as requested.

[coderabbitai]

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commit: 4d84212