fix(core): honor ignoreScripts for git dependency preparation - #60201

Measured what honouring ignoreScripts means here, because it changes what "installed" is for plugins that build themselves.

With @npmcli/arborist directly, same options as Npm.reify, on a Git dependency whose prepare compiles the entry point:

So the guard removes the error but ships the dependency unbuilt. For a plugin with main: ./dist/index.js, that file does not exist afterwards and OpenCode loads nothing: a silent failure where today there is a loud one, for every plugin that compiles during install.

The preparation does not fail because building is unwanted — it fails because the child process is wrong. pacote spawns process.execPath with /$bunfs/bin/npm-cli.js when npmBin ends in .js, and the binary runs its CLI instead of that script (the strace is in #49704).

Suggestion: keep this guard as the fallback for machines with no npm, but try the preparation first with a resolved npm, and when it is skipped for lack of one, say so instead of reporting success. #62817 does the first half.

@JoshRob297 is right, and the measurement settles it. Skipping preparation makes the install succeed while leaving the package unbuilt, so a plugin with main: ./dist/index.js resolves to a file that does not exist — a silent failure in place of a loud one. My test here asserts exactly that skipped-script behaviour, which means it was pinning down the wrong contract.

The preparation step is not the problem; the child process is. #62817 fixes that by resolving a real npm instead of a path into the bundle, which is the cause rather than the symptom. Closing this in favour of it.