test: accept npm 12 script output

[anusbutt]

Outcome

Keep the clean-source onboarding release test compatible with npm's newer script banner.

npm 12 prints npm notice run graphkeeper@0.4.0 typecheck instead of the older > graphkeeper@0.4.0 typecheck. The test now checks the stable package/version/script identity without coupling to npm's cosmetic prefix.

No production, package, schema, validator, hook, documentation, or version behavior changes.

Evidence

Before:

• The release prepublish run passed 302/303 tests.
• contributor-onboarding.test rejected the npm 12 banner because it required a leading >.

After:

• Focused WSL onboarding suite: 2/2 passed.
• Native typecheck/build passed.
• The native focused run reached an unrelated existing jq process timing boundary after the changed assertion had passed; required Windows CI remains authoritative.

Checklist

• One focused test assertion changed.
• Production behavior is untouched.
• Schema and diagnostics are unchanged.
• No generated archives or unrelated edits are included.
• Publication and tagging remain paused pending merge and release verification.

Compatibility and recovery

The assertion accepts both the established npm output and npm 12's new npm notice run output because both contain the same stable graphkeeper@<version> typecheck identity. No recovery or repository migration is required.